At high temperature, Mg can reduce not only carbon in the oxidation state of +4 in CO32− to form graphene, but also sulfur in SO42− from its highest (+6) to lowest valence which was hybridized into the carbon sp2 framework. Various characterization results show that sulfur-doped graphene with only few layers has an appropriate sulfur content, hierarchically robust porous structure, large surface area/pore volume, and highly graphitized textures. The S-doped graphene samples exhibit not only a high activity for ORR with a four-electron pathway, but also superior durability and tolerance to MeOH crossover to 40% Pt/C. This is mainly ascribed to the combination of sulfur-related active sites and hierarchical porous textures, facilitating fast diffusion of oxygen molecules and electrolyte to catalytic sites and release of products from the sites.Efficient metal-free electrocatalysts for oxygen reduction reaction (ORR) are highly expected in future low-cost energy systems. We have successfully prepared crumpled, sheet-like, sulfur-doped graphene by magnesiothermic reduction of easily available, low-cost, nontoxic CO CO2 emitted from fuel-fired power plant is captured by a well-developed chemical absorption process using aqueous amine-ammonia solutions in industrye.g. zeolites45etc) and CO2 moleculesBecause of the predicted detrimental effects  of a cell with the conventional graphene via chemical exfoliation of graphite2 (in the form of Na2CO3) in the presence of Na2SO4 as an inorganic sulfur source to graphitized, wrinkled, sulfur-doped graphene with only few layers.Except for CO2-hybridized carbon)18212325e.g. nitrogen , phosphorus , sulfur , boron , etc) with distinct electronegativity with respect to carbon atoms (electronegativity: 2.55) into sp2-hybridized carbon frameworks can remarkably modify their electronic structures and chemical activities as well as the Fermi level of the host. This strategy is simple and efficient to improve the properties of graphene. At the same time, the robust framework and most of the intrinsic properties of graphene are maintained after the doping of the heteroatoms. Chemical vapor deposition (CVD) and the solvothermal pathway have been adopted to produce doped graphene using liquid precursors27e.g. ureaetc). Compared to N- (or B-) doped graphenes, little attention has been paid to the doping of S atoms into the graphene framework3334Since the seminal work of Geim and co-workers on the preparation of single layer graphene (sp2 carbon lattice by two procedures: (I) CVD technique using liquid organics and (II) the pyrolysis of GO and S-containing precursors. For example, Gao and co-workers reported the formation of S-doped graphene on Cu foil using liquid S-hexane mixture vapor at 950°C332S, SO2 or CS2 gas is an efficient procedure of doping graphene lattice with S atoms342S-treated GO at 500 ~ 900°C has the content of 1.2–1.7 at% S, which was employed as metal-free electrocatalysts for ORR40412S, SO2 and CS2) gas flow as the S source could result in the production of large amount of exhaust waste. It is, however, yet a big challenge to directly generate S-doped graphene from easily available, low-cost, nontoxic Na2CO3 and Na2SO4 inorganic oxide salts as the C and S sources, respectively.S-containing functionalities have been successfully incorporated into the sp2 (in the form of Na2CO3) in the presence of small amount of Na2SO4 as an inorganic S source to form S-doped graphene, as shown in 32− to form black graphene products. At the same time, the SO42− ions could supply S atoms to build C-S sp2 bonds integrated into the graphene lattice; S in its highest oxidation state of +6 in SO42− is reduced to the lowest valence by Mg metal. It is observed that S-doping has a great influence on the morphologies of graphene sheets. Thus, the present novel procedure can efficiently reduce the CO2 concentration in the atmosphere by chemically fixing carbon in CO2 to valuable doped, high-quality graphene. We also showed that the as-formed S-doped graphene materials demonstrate high electrocatalytic activity for ORR with a dominant four-electron reaction pathway, as well as excellent durability and MeOH crossover compared to commercial Pt/C catalyst. Thus they can be considered as ideal candidates as metal-free ORR electrocatalysts.Herein, we have employed a one-step magnesiothermic reduction strategy to transform greenhouse gas CO2CO3, the product has a dark black color, suggesting the formation of a graphitic structure. 2CO3 at 800°C (CG-800), observed by scanning electron microscopy (SEM). Low-magnification SEM image shows that CG-800 has a loose, porous structure . SG-800 exhibits a similar morphology to that of CG-800, confirmed by low-magnification SEM image  crystal plane (0.335 nm) of bulk graphite due to slight expansion and distortion47at%) as well as O (3.6 at%) element in the graphene layers. Also, small amount of Na and Cl elements were found, which are mainly due to the trapped Na compounds between the graphene layers during the magnesiothermic reaction and the following acid-washing stepFurther observation on the morphology difference between pure graphene and S-doped graphene was confirmed by transmission electron microscopy (TEM). As shown in 0 layers . In Figuat% (ca. 0.5 ~ 0.6 at%) prepared by the pyrolysis of GO and BDS2S at high temperatures342-bonded carbons, exhibiting that all of them possess a crystalline graphene structure. Indeed, two strong and broad characteristic peaks can be observed at 26.1 and 43.3 degrees arising from the (002) and (100) planes of graphene sheets, respectivelyd-spacing of (002) crystal plane is about 0.35 nm, slightly larger than the interlayer spacing in graphite (0.335 nm). These results match well with those from TEM analysis, implying the formation of high-quality graphene structures in SG-800. In contrast, magnesiothermic reduction of CaCO3 at 800°C led to the production of amorphous carbons rather than crystalline graphene2CO3 is better carbon source for the synthesis of graphene nanostructures.In accordance with EDS analysis, X-ray photoelectron spectroscopy (XPS) survey scans of S-doped graphenes prepared at different temperatures imply the varied S contents of 1.8 ~ 2.6 at% . The S cat% 16. After2 graphitic layer) bands at ~1560 cm−1, D (related to defect in sp2 lattice) bands at ~1350 cm−1, and 2D bands at ~2725 cm−1 in the spectrum (ID/IG) is used to evaluate the defect content of the graphene. As shown in ID/IG for the resulting S-doped graphenes lower. For example, the value of ID/IG is 0.75 for the sample prepared at 700°C, and it decreases to 0.47 for SG-800, and further to 0.41 for SG-900. This implies that a higher reaction temperature is favorable for defect repair to form graphene with more perfect layers. Furthermore, it can be found that the ID/IG values of the resulting graphene materials are evidently higher than those of most chemically reduced GO−1) of CG-800 is shifted down to 1570 cm−1 for SG-800, which is an important characteristics of n-type doping of graphene by the substitution. The similar red shift is also reported for N-doped graphene49−1) for S-doped graphenes are significantly lower than 2725 cm−1 for pure graphite, showing the successful preparation of few-layer graphene nanostructures in all samples. When increasing reaction temperatures, the 2D position (2685 cm−1) for SG-700 shifts down to 2678 cm−1 for SG-800, and 2676 cm−1 for SG-900, respectively. It indicates that SG-800 and SG-900 have similar average numbers of the graphene nanosheets, both of which are smaller than the average numbers for SG-700.Further structural information about S-doped graphenes was obtained from Raman spectroscopy technique through the determination of the G  surface area, total pore volume, and pore size distribution. The corresponding nitrogen adsorption-desorption isotherms and pore size distributions for S-doped graphenes and pure graphenes are shown in 2/g and 1.887–1.936 cm3/g, respectively. These data slightly decrease to 188–199 m2/g and 1.383–1.604 cm3/g, respectively, for S-doped samples compared with those of pure graphenes. Among these S-doped graphenes, the sample prepared at 800°C demonstrates the largest specific surface area and pore volume. The specific surface areas of these graphenes are significantly lower than the theoretical surface area of 2630 m2/g for individual isolated graphene sheets0) of 0.45–1.0, which might be a result of small mesopores and intersheet textural large pores. The pore size distribution curves of pure graphenes and S-doped graphenes calculated by the Barrett-Joyner-Halenda (BJH) model, show a single well-defined peak at 3.8 nm in all curves, implying that all graphene samples have narrow mesopores. It is noted that a weak peak is found at about 35 nm, possibly ascribed to the intersheet textural pores.To get insights in pore structures of the resulting graphenes prepared by magnesiothermic reduction, the N2 carbon in the samples. Furthermore, there are very minor shoulder contributions to the XPS signals at binding energies of 286.0–288.0 eV, which are assigned to sulfur- and/or oxygen-bound carbon atoms on the material surfacee.g. S dominated in the graphene framework via the formation of the sulfide bridges (-C-S-C)2SO4 could be reduced to its lowest valence, which is then hybridized into the graphene layers during the magensiothermic reduction.To further investigate the chemical environments of S and C atoms in the graphene layers, high-resolution X-ray photoelectron spectroscopy (XPS) spectra in the C1s and S 2p regions were recorded in in-situ reactive doping of S into the graphene framework could be accomplished by magnesiothermic reduction of Na2CO3 in the presence of Na2SO4 as an inorganic S source. It is believed that Mg could reduce not only CO32− to the graphitized carbons, but also S in the highest oxidation state of +6 in SO42− to the lowest valence which was further hybridized into the carbon sp2 framework. The addition of Na2SO4 during the magnesiothermic reduction evidently not only affects their structure and morphologies, but also improves the electrocatalytic performance of the resulting S-doped graphenes for ORR as discussed below. The present S-doped graphenes possess an appropriate S content, hierarchical porous textures, and highly graphitized structure. Such unique features will promote fast access of oxygen molecules to the catalytic sites and can favor the swift diffusion of electrons in the electrode during the ORR process.It has been reported that S-doped graphenes could act as metal-free electrocatalysts for ORR. In present work, it has been proved that the 2- and O2-saturated 0.1 M KOH aqueous electrolyte at a scan rate of 50 mV/s. It was found that ORR on a GCE requires large over potentials ) with very low oxygen reduction current density (−0.38 mA/cm2); this reduction current was reported to be the two-electron reduction process of O2 to peroxide which is electrochemically mediated by the oxygen-containing groups at the surface of bare GCE. The CVs for S-doped graphenes exhibit nearly rectangular shapes, showing high conductivity with superior capacitive current. A well-defined oxygen reduction peak at ~−0.32 V (vs. SCE) is observed for S-doped graphenes in O2-saturated 0.1 M KOH solution, while there is no such a peak in N2-saturated one, indicating that O2 is reduced on S-doped graphenes  significantly increases, corresponding to methanol electro-oxidation. In contrast, no noticeable change except for a slight decrease in the current density of ORR is found for SG-800 under the same conditions. These voltammograms show that S-doped graphenes have higher selectivity for ORR with a remarkable improved ability to avoid the cross effects than commercial Pt/C. It is mainly ascribed to the highly graphitized nanostructures, which increase both the electronic conductivity and corrosion resistance of SG-800. Thus, this kind of S-doped graphenes has great potentials as the electrocatalytic material in direct methanol and alkaline fuel cells.To examine the possible crossover effects, the electrocatalytic selectivity of SG-800 and 40% Pt/C against electro-oxidation of methanol  by CVs in an O3 M MeOH . The cur2-saturated 0.1 M KOH aqueous solution at different rotating speeds on a rotating disk electrode (RDE) (sweep rate: 5 mV/s). The voltammetric profiles show that the current density is increased with an increase in rotating speeds . The S doping into the graphene framework evidently results in the positively shift of the onset potential from −0.18 V (vs. SCE) for pure graphene to −0.15 V (vs. SCE) for S-doped graphene. It implies the important role of S atoms doped into the graphene layers in adjusting chemical/electronic properties of graphene, thus improving the ORR catalytic performance of S-doped graphene. All S-doped graphene samples show the onset potentials are just negatively shifted by 0.12 V (vs. SCE) related to that (−0.04 V vs. SCE) for commercial Pt/C (e. g. N-doped graphene29etc) for ORR (vs. SCE) are significantly higher than those for all pure graphenes, strongly indicating that S atoms have been doped into the layers of graphene sheets, and have similar impact to nitrogen atoms doped into the graphene layers on the electronic structure of doped graphenes. Among these graphene samples, SG-800 demonstrates the largest ORR current density (3.3 mA/cm2) at −0.32 V , which are evidently superior or compared to heteroatom-doped porous carbon-based electrocatalysts for ORR  in an Og speeds . The corlectable , indicatial Pt/C . This va for ORR . Notably for ORR . The higvs. SCE) exhibit good linearity, the slopes of which are approximately constant. It also indicates the first-order reaction kinetics with respect to the concentration of O2 dissolved. The exact electron transfer numbers of S-doped graphene and CG-800 were calculated according to the slopes of the linear fitted K-L plots on the base of the K-L equations as followingJ and Jk are the measured current density and kinetic-limiting current density, respectively, n is the electron transfer number, F is the Faraday constant (96485 F/g), v is the viscosity of the electrolyte (0.01 cm2/S), CO2 is the concentration of O2 (1.2 * 10−6 mol/cm3), and DO2 is the diffusion coefficient (1.9 * 10−5 cm2/s). The coefficient 0.2 is adopted when the rotating speed is expressed in rpm. As displayed in 2 molecules (n = 3.1 ~ 3.8) in ORR is higher than two in the potential range of −0.5 V to −0.6 V, and SG-800 has the highest electron transfer numbers (3.7–3.8), possibly because of its highest surface area and pore volume and appropriate S content. This result indicates that the desirable four-electron reduction process for SG-800 to form water as the main product other than peroxide is predominant. In contrast, CG-800 has n value of ca. 2.2, which suggests that the two-electron reduction process with peroxide as the main product is dominant. Note that four-electron process is very important for ORR in fuel cells, because peroxides can poison the cell. This finding matches well with previous reports indicating that pure reduced GO can cause a two-electron pathwayBy using the Koutecky-Levich (K-L) equation, we further analyzed the RDE data collected by LSVs. As shown in vs. SCE) in O2-saturated 0.1 M KOH solution at a scan rate of 200 mV/s, implying the excellent capacitance stability of SG-800. Moreover, we also conducted a 3.5 h stability test for SG-800 and 40% Pt/C toward ORR using the i-t chronoamperometric response at a constant voltage of −0.4 V (vs. SCE) in a O2-saturated 0.1 M KOH solution at a rotating speed of 1600 rpm. As shown in 2SO4 as the S source is compared to commercial Pt/C for ORR.Another major concern is the stability of the S-doped graphene used as high-performance electrocatalyst for ORR. Accordingly, the continuous potential cycling to investigate the stability of SG-800 was performed. As shown in 2 into the atmosphere. By magnesiothermic reduction of Na2CO3 and Na2SO4 as low-cost, nontoxic carbon and sulfur sources, respectively, S-doped graphenes with few layers have been successfully prepared. The melting Mg can reduce carbon in the oxidation state of +4 in carbonate to form black graphene products. And sulfur in sulfate also can be reduced from its highest oxidation state to lowest valence and hybridized into the carbon sp2 framework. The resulting graphenes possess crumpled, sheet-like nanostructures with hierarchically porous textures and the addition of sulfate during the magnesiothermic reaction results in the formation of S-doped graphenes with more distorted nanostructures. The sulfur doping of the graphene framework evidently decreases the ORR onset potentials and increases limited current densities compared with pure graphenes. The resulting S-doped graphenes demonstrate not only high electrocatalytic activity for ORR with a four-electron reaction pathway, but also much better stability and increased tolerance to MeOH crossover effects than commercial Pt/C. The high activity for ORR of S-doped graphenes is mainly ascribed to highly graphitized structures, S-related active sites, and hierarchically porous textures. The present magnesiothermic reduction procedure is being investigated in the preparation of other heteroatom-doped (e.g. P and B) graphene materials potentially utilized in the fields of electrocatalysis, batteries, supercapacitors, biosensors, etc.In summary, this work has shown an efficient strategy to chemically fix carbon to form valuable, high-quality, doped graphenes, which also can efficiently reduce the emission of CO2CO3 and Na2SO4 were used as the C and S sources, respectively, and magnesium (Mg) powder were utilized as the reducing reagent. A calculated amount of these powders were mixed together and then put onto an alumina boat which was inserted into a stainless steel tube. The reaction temperature was controlled to be 700, 800, or 900°C for 1 h at a ramp of 5°C/min under argon (Ar) atmosphere. After cooling to room temperature, the resulting black solids were dispersed in sufficient 10% HCl solution and vigorously stirred for 4 h to remove any inorganic impurities. The carbon was collected by filtration and purified by distilled water and ethanol for three times each. Finally, the filtered product was dried at 80°C overnight and further annealed in Ar atmosphere. And the resulting S-doped graphene was denoted as SG-X, where SG is the abbreviation of S-doped graphene and X stands for the magnesiothermic reaction temperature in °C. For comparison, pure carbon-based graphene (CG) samples were synthesized by magnesiothermic reduction of Na2CO3 without any Na2SO4.Anhydrous Nahυ = 1486.6 eV) radiation. The graphene powders were glued onto indium (In) metal particles by pressing for measurements. All spectra were calibrated using 285.0 eV as the line position of adventitious carbon. Nitrogen sorption isotherms were measured using a Micromeritics ASAP 2010 surface area and pore size analyzer at liquid nitrogen temperature (−196°C). Prior to measurement, the hierarchically porous materials were dehydrated under vacuum at 200°C overnight. The specific surface areas were calculated by the Brunauer-Emmett-Teller (BET) method. The total pore volume was calculated from the amount of nitrogen adsorbed at a relative pressure of 0.99. The pore size distribution curves were calculated from the analysis of the desorption branch of the isotherm using the Barrett-Joyner-Halenda (BJH) model.Transmission electron microscopy (TEM) images of the graphene were recorded using a JEOL 2010F electron microscope equipped with an energy dispersive spectrometry (EDS) attachment operating at 200 kV. Samples for analysis were deposited on a thin amorphous porous carbon film supported by copper grid from ultrasonically processed ethanol solutions. The morphology of the graphene was observed by scanning electron microscopy (SEM) using a field emission microscope . Samples were mounted using a conductive carbon double-sided sticky tape. Raman spectra were recorded on a DXR Raman Microscope  with 532 nm excitation length. X-ray powder diffraction (XRD) measurements were carried out on a Rigaku D/MAX-2250 V diffractometer with Cu Kα radiation. X-ray photoelectron spectroscopy (XPS) was recorded with an ESCALAB 250 X-ray photoelectron spectrometer with Al Kα (ca. 2 h. Then 5% Nafion solution (25 μL) was added into the above suspension, and the further ultrasonic treatment was performed until a homogeneous ink was formed. 20 μL ink containing 62.5 μg catalyst was transferred onto the glassy rotating disk electrode with 5 mm diameter, yielding a catalyst level of 0.32 mg/cm2. For 40% Pt/C commercial catalyst (JM company), 31.2 μg catalyst was deposited on the glassy rotating disk electrode. The electrode with the catalyst was dried at 50°C which was used as the working electrode for further electrochemical measurements. Electrochemical activity of the working electrode was studied by cyclic voltammetry (CV) and rotating disk electrode (RDE) using a standard three-electrode cell with a Pt plate as the counter electrode and a saturated calomel electrode (SCE) as the reference electrode. An aqueous solution of 0.1 M KOH was used as the electrolyte for the electrochemical studies. The electrochemical cell was controlled by a bipotentiostat (Pine Instrument Co.) equipped with a RDE. Prior to the measurements, the electrolyte was saturated by bubbling O2 or N2 for 15 min. The working electrode was cycled at least thirty times before the CV data were recorded at a scan rate of 50 mV/s. The RDE measurements were performed at different rotating rates varying from 400 to 2025 rpm with the scan rate of 5 mV/s.The graphene sample (5 mg) was dispersed in the mixture of 0.5 mL water and 0.5 mL ethanol under ultrasonic irradiation for J.W. performed the experiments, and wrote the manuscript; R.M., Z.Z. and G.L. analyzed the data; Q.L. designed the experiments; all authors reviewed the manuscript.supporting information


With the support of SiO2, the stacked interlamination of graphene was held open to expose the powerful adsorption sites in the interlayers. The adsorption of phenanthrene, a model aromatic pollutant, onto the loaded graphene nanosheets increased up to 100 fold compared with pristine graphene at the same level. The adsorption of GCMs increased with the loading amount of the graphene nanosheets and dramatically decreased with the introduction of oxygen-containing groups in the graphene nanosheets. The highly hydrophobic effect and the strong π-π stacking interactions of the exposed graphene nanosheets contributed to their superior adsorption of GCMs. An unusual GCM peak adsorption coefficient (Kd) was observed with the increase in sorbate concentration. The sorbate concentration at peak Kd shifted to lower values for the reduced graphene oxide and graphene relative to the graphene oxide. Therefore, the replacement of water nanodroplets attached to the graphene nanosheets through weak non-hydrogen bonding with phenanthrene molecules via strong π-π stacking interactions is hypothesized to be an additional adsorption mechanism for GCMs.The substantial aggregation of pristine graphene nanosheets decreases its powerful adsorption capacity and diminishes its practical applications. To overcome this shortcoming, graphene-coated materials (GCMs) were prepared by loading graphene onto silica nanoparticles (SiO This type of composition has been used in solid-phase extraction material2 and the effects of graphene loading percentage on their adsorption performance need to be investigated for practical fabrication and environmental applications; and the true potential of the adsorption mechanisms of the loaded graphene nanosheets need further elucidation to consider the effects of OCGs on the graphene-water interface. Silica (SiO2) is an ideal framework material for mitigating graphene aggregation because it is an inexpensive, nontoxic and widespread material that can be manufactured in megatons per year302 in the environment, interactions between SiO2 and graphene are unavoidable when graphene is discharged into the environment. Thus, the adsorption capabilities and mechanisms of graphene-coated silica composites with different loadings and various OCG contents are worth further investigation.One promising strategy is to develop graphene-based materials by loading graphene nanosheets onto low-cost substrates192 particles with different loading percentages to probe the effects of graphene loading percentages and the OCG contents. The structures of SiO2, NH2-SiO2, pristine graphene and GCMs were characterized by elemental analysis, surface area, surface charge, FTIR, SEM and TEM to reveal the materials’ microscopic properties. Phenanthrene was selected as a model aromatic pollutant to determine the materials’ adsorption abilities and as a probe molecule to understand the interaction mechanisms at the graphene-water interface. In addition, the roles of attached water molecules on different graphene-water interfaces are discussed.The main objective of this study is to fabricate a highly efficient graphene-based adsorbent for organic pollutant management. To optimize practical performance of graphene materials in pollutant management, a series of GCMs were prepared by loading graphene oxide (GO), reduced graphene oxide (rGO) and graphene (G) nanosheets onto SiO2-SiO2 (surface area = 109 m2/g) can support 82.9 mg of monolayer graphene (surface area = 2630 m2/g) at maximum degree. Four different SiO2-graphene ratios  were designed to investigate the maximum loading percentage considering the surface area reduction of NH2-SiO2 caused by aggregation. As presented on 2-SiO2 (positive) and graphene oxide (negative) were oppositely charged at pH 1 to 8; thus, the self-assembly of graphene oxide on NH2-SiO2 was easily performed via electrostatic interactions. The synthesis pH was controlled at 7 to maintain the maximum surface potential difference between graphene oxide and NH2-SiO2, according to surface potential analysis. The digital images presented in 2, as well as the fact that not all of the graphene oxide completely combined with the SiO2. Once the loading percentage surpassed 2%, large quantities of graphene oxide were suspended in the supernatant  and with various degrees of reduction . The macroscopic morphologies of the obtained GCM powders are shown in 2 was added. In this case, no graphene oxide was dissolved, even after ultra-sonication  of graphene sheets. The surface areas of GCMs largely depended on SiO2, when graphene was wrapped around SiO2 particles. There were no changes in the surface area of GCMs with different reduction processes and loading percentages. After wrapping, the loaded graphene was unfolded after being attached to the surface of the SiO2, which was demonstrated by the SEM and TEM investigations /(mg/L)N] is the Freundlich affinity coefficient, N is the exponential coefficient, Qe (mg/g) is the equilibrium adsorption concentration of the sorbent, and Ce (mg/L) is the equilibrium solution phase concentration of the sorbate. According to the regression coefficient (R2), the isotherms of the nine different graphene-based materials were well fitted by the Freundlich model. The Freundlich N index was 0.698−0.612 for ASGO at 100:0.5, 100:1 and 100:2, and decreased to 0.387−0.324 for ASrGO and ASG, suggesting that the surfaces of the ASrGO and ASG were more heterogeneous than those of ASGO. The adsorption of GCMs increased as the number of OCGs on the graphene nanosheets decreased (where ecreased  and increcreased . These o2-SiO2. Based on Qe) at Ce/Cs = 0.01 was 3.62 × 10−2 mg/g for ASGO (100:2) which was approximately 660 times higher than that of SiO2 (5.44 × 10−5 mg/g)Qe at Ce/Cs = 0.01 for ASrGO (100:2) further increased to 1.08 mg/g and up to 1.74 mg/g for ASG (100:2) after deeper chemical reduction. The adsorption capacity of ASG (100:2) was approximately 32,000 times greater than that of bare SiO2. Meanwhile, the exact graphene content in ASG (100:2) was only 2.35% according to the elemental analysis. Considering the widespread existence of SiO2 in the environment and the mass production of graphene, the combination of graphene and SiO2 is unavoidable. Companied with graphene’s commercial process, this dramatic improvement in the adsorption of SiO2 should increase our focus on controlling graphene as an environmental risk. Similarly, the adsorption capacity of GCMs with loading percentages of 100:1 and 100:0.5 (Qe of pristine graphene (2.45 mg/g at Ce/Cs = 0.01)2 with phenanthrene, the adsorption capacity of graphene in ASG (100:2) was 73.73 mg/g, which was 30 times greater than that of pristine graphene (2.45 mg/g) (based on the same graphene content at Ce/Cs = 0.01). This surprising increase indicated that the potential adsorption capacity of the well-dispersed graphene was successfully exposed in higher graphene loading percentage and that the results were higher than the relevant data presented in previous reports1723According to the loading percentage test, the maximum graphene loading degree is 2% under which graphene oxide can mostly be loaded onto the surface of NH 100:0.5  increase2 produced a synergistic effect in aromatic pollutant removal, and the large-scale improvements in the adsorption of graphene suggested that wrapping graphene around SiO2 particles is a facile method for using graphene to manage environmental pollution. In addition to the degree of reduction, the influence of the graphene loading percentage on the adsorption performance was also investigated , ASG (100:1), and ASG (100:2) were 0.424, 0.775, and 1.74 mg/g, respectively, at Ce/Cs = 0.01. When normalized by the graphene contents of the GCMs, the adsorption of phenanthrene onto wrapped graphene in ASG (100:0.5), ASG (100:1) and ASG (100:2) were 71.86, 52.01 and 73.73 mg/g, respectively, at Ce/Cs = 0.01. This excellent adsorption performance illustrates that the potential adsorption ability of the graphene nanosheets was readily available after the graphene was applied to silica particles under the loading ratio below 2%. Because the adsorption performance of the GCMs was influenced by the synthesis conditions, the ratio of graphene to SiO2, and the oxygen content in the graphene surfaces, this study provides a reference for fabrication parameters in designing optimal graphene-coated materials for potential environmental applications.The combination of graphene and SiOstigated . The Qe Kd = Qe/Ce) was introduced. To better exhibit the mutual interaction mechanism beyond the hydrophobic effect, the normalized adsorption coefficient (Kd) relative to the hexadecane-water partitioning coefficient of phenanthrene (KHW = 35481 L/kg) was also applied17Kd/KHW values of phenanthrene adsorption on the GCMs are presented in Kd/KHW values of phenanthrene adsorption on ASG (200:0.5) was cited from our previous study for comparisonKd/KHW ratio increased with the sorbate equilibrium concentration and formed a sharp peak at relatively low concentration ranges. This uncommon phenomenon for the adsorption of GCMs occurred by varying the concentrations of the sorbate over 3 orders of magnitude rather than over a narrow concentration range. The increase in Kd/KHW with increasing sorbate concentration suggests that greater surface energy adsorption sites were created on the graphene nanosheets during the initial adsorption stage. With more phenanthrene attached to the graphene surface, the original and subsequently created sites were gradually occupied, resulting in a decline in the Kd/KHW. A sharp peak in Kd/KHW appeared for all ASGO, ASrGO, and ASG samples. The turning point clearly shifted to lower equilibrium concentrations from ASGO, to ASrGO, and further to ASG, with enhanced reduction degree Kd/KHW values based on the graphene contents of different GCMs are compared in Kd/KHW values of phenanthrene on ASrGO (100:2) and ASG (100:2) were approximately 75 and 205 times greater, respectively, than that of ASGO (100:2). The maximum Kd/KHW ratio of graphene in ASG (100:2) was 1280, which was approximately 100 times greater than that of pristine graphene. However, the enrichment capacity of loaded graphene with regard to aromatic molecules was almost 1000 times higher than biological interfaces, which can be determined because KHW is widely used as a surrogate to simulate organic molecule partitioning on biological interfacesKd/KHW (1280) for phenanthrene on ASG was much higher than for other popular adsorbents, such as single-walled carbon nanotubes (maximum Kd/KHW = 280 for phenanthrene)Kd/KHW = 0.493)Kd/KHW  = 1.13 × 10−3)Kd/KHW = 1.83 × 10−4)Kd/KHW = 1.13 × 10−3)Kd/KHW = 0.564 and 0.324–1.27)402 nanoparticles acted as a superior sorbent for aromatic pollutant removal.Based on 2 nanoparticles are known to possess a hydrophilic surface with a large quantity of –OH322 nanoparticles are naturally covered by a hydration shell30312 surface, the adsorption of phenanthrene onto SiO2 in the aqueous solution was minimal. The Freundlich N index of SiO2 (1.06)2 and phenanthrene primarily resulted from the distribution effect2 involved its transfer from the bulk liquid phase to the vicinal water phase2 showed little change because the bound –NH2 was a monolayer and multiple –OH groups were preserved2 particles, the adsorption capacity of the GCMs significantly improved. This improvement was mainly attributed to the existence of graphene nanosheets acting as a hydrophobic cloth. Once wrapped, the hydrophilic surface of the SiO2 particles became hydrophobic and possessed an additional π-electron conjugated structure. The strong π-π interaction between the phenanthrene and graphene nanosheets was accompanied by a hydrophobic interaction, replacing the weak distribution behavior in the vicinal water phase. Consequently, the GCMs displayed an excellent affinity for phenanthrene.As a well-studied nanomaterial, SiO2 particles, the adsorption capacities of the coated graphene on the SiO2 significantly improved relative to pristine graphene at the same concentration. After wrapping around the surface of the SiO2 particles, the microscopic morphology of graphene was loose and porous 4845472 substrate, both highly oriented water clusters and water adsorbates can lead to graphene dopingIn aqueous solutions, water molecules are unavoidable adsorbates on hydrophobic surfaces of graphene nanosheets4546et al. also suggested that aromatic molecules may be better aligned on graphene sheetsKd/KHW values at low concentration ranges and may provide new insights into the phenanthrene adsorption mechanisms at the graphene-water interface.The hydrated shell functions as a hydrophilic barrier to weaken the hydrophobic character of the graphene and further prevents π-π interactions between the phenanthrene and the graphene oxide surface . TherefoKd/KHW values shifted to lower values from ASGO to ASrGO and ASG.The distributions of water clusters and water microdroplets/nanodroplets are regulated by oxygen-containing groups, which are influenced by the degree of reduction of the graphene-coated materials. During the reduction process, the π electron structure and hydrophobic surface of the graphene are recovered17502 particles, which then act as a framework. The potential adsorption sites concealed in stacked graphene were exposed in the GCMs, strongly enhancing the adsorption of the graphene nanosheets. Through surface potential manipulation, the potential adsorption capacity can be well expressed at its maximum loading degree (2%). Additionally, the separation of hydrophobic and hydrophilic graphene materials from water improved when SiO2 particles were used. The water molecules (microdroplets) attached to the exposed graphene nanosheets via non-H bonds are easily replaced by phenanthrene molecules, and the displacement efficiency can be regulated by oxygen-containing groups of graphene nanosheets. The graphene nanosheets and silica particles produce a synergetic effect in pollutant-removing GCMs, presenting a facile method for large-scale production of graphene-coated materials. Graphene-coated materials using silica particles as a framework are cost-effective and highly efficient adsorbents for removing aromatic pollutants from water and will result in enormous opportunities for using novel 2D nanomaterials (graphene) for environmental applications.The substantial aggregation of graphene nanosheets can be easily overcome via the coating of SiO2 nanoparticles were first modified using a silane coupling agent (APTES) to transform the surface potential by binding monolayer –NH22 particles were dispersed in deionized water (50 mL) by stirring. A selected concentration of graphene oxide solution (50 mL) was prepared using ultrasonication. Subsequently, the graphene oxide solution was gradually added to the mixed NH2-SiO2 colloids using continuous mechanical stirring. The whole process was kept at 35 °C for 1 h, and the final pH was controlled at 7. After completion of the reaction, the mixture was undisturbed for 2 h to observe the settling situation. The final aminosilica-supported graphene oxide (ASGO) was collected through filtration, washed with water and dried under vacuum. The loading percentage of graphene was controlled by modulating the initial concentration of the graphene oxide solution and was determined by elemental analysis. ASGO (100:0.5) was synthesized by adjusting the initial concentration of the GO solution to 0.1 mg/mL to obtain the SiO2-to-GO ratio of 100:0.5. GO solutions of 0.2 mg/mL, 0.4 mg/mL and 0.8 mg/mL were used for ASGO (100:1), ASGO (100:2) and ASGO (100:4), respectively.Graphene oxide (GO) was prepared from natural graphite flakes using a modified version of the Hummers method2, respectively. Compared with solvothermal reduction, the degree of deoxygenation via chemical reduction was much higherSolvothermal reduction and chemical reduction were used to deoxygenate of graphene oxide in the ASGO to prepare the reduced graphene oxide (rGO) and graphene (G) loading on SiO2 adsorption-desorption at –196 °C with a NOVA-2000E surface area analyzer and were calculated using the multipoint Brunauer-Emmett-Teller (BET) method. The exact concentrations of C, H, and N were determined using an EA112 CHN elemental analyzer (Thermo Finnigan). The surface charge properties were evaluated at different equilibrium pH values using a Malven Zetasizer analyzer. The surface functional groups were monitored with a Bruker Vector 22 FTIR spectrometer at a resolution of 1 cm−1 using a mixture of 1 mg graphene-coated materials and 200 mg KBr. The surface morphologies and structures were characterized using an S-4800 field-emission scanning electron microscope (FE-SEM)  and a high-resolution transmission electron microscope (HR-TEM) . For the FE-SEM observations, samples were placed on the conductive base without any extra treatment to detect the actual morphologies and gold nano-film was sprayed for better conductivity. For the HR-TEM observations, the samples were dispersed in a water solution to yield individual particles and dropped onto the micro grid network.The surface areas of the GCMs were measured using N2 and 200 mg/L NaN3 to control the ionic strength and inhibit microbial activity). For any given GCM, the adsorption capacities obtained after 36 h and 72 h were the same, suggesting that equilibration was achieved before 36 h. Isothermal experiments with different materials were conducted at selected water-to-solid ratios to maintain removal percentages of 20%–80%. Different volumes of phenanthrene in acetonitrile were dissolved in the background solution to achieve the desired concentration. The volume of acetonitrile in the background solution was maintained at less than 0.1% to avoid cosolvent effectsPhenanthrene was selected as the model aromatic pollutant to explore the adsorption capacity of GCMs with different loadings and various oxygen contents. Adsorption experiments were conducted at room temperature (25 ± 1 °C) in a background solution .


The progression of amyotrophic lateral sclerosis (ALS) through the brain has recently been staged using independent neuropathological and neuroimaging modalities. The two schemes tie into the concept of pathological spread through corticofugal axonal transmission that stems from observation of oligodendrocyte pTDP-43 aggregates along with neuronal inclusions. Here, we aimed to assess evidence of transmission along axonal pathways by looking for pTDP-43 oligodendrocyte pathology in involved white matter tracts, and to present a first validation of the neuropathological staging scheme.N = 34). Double-labelling immunofluorescence was performed to confirm co-localisation of pTDP-43 immunoreactivity to oligodendrocytes.pTDP-43 immunohistochemistry was performed in select white matter tracts and grey matter regions from the staging scheme in postmortem-confirmed ALS cases  and disease duration (shorter duration than Stage 3 and similar to Stage 2).Four stages of ALS neuropathology can be consistently identified, although evidence of sequential clinical progression requires further assessment. As limited pTDP-43 oligodendrocyte pathology in deep corticospinal and other white matter tracts from the motor cortex was observed, the propagation of pathology between neurons may not involve oligodendrocytes and the interpretation of the changes observed on neuroimaging should be modified accordingly.The online version of this article (doi:10.1186/s40478-015-0226-y) contains supplementary material, which is available to authorized users. Motor neuron disease covers a group of neurodegenerative disorders that affect different parts of the motor system, be it the upper motor neurons in the primary motor cortex and brainstem or the lower motor neurons in the spinal cord. Amyotrophic lateral sclerosis (ALS) with both upper and lower motor neuron involvement is the most common presentation, accounting for more than 75 % of cases with motor neuron disease , 2. The Recently, Brettschneider and colleagues defined four neuropathological stages of ALS , proposiThe idea of disease propagation from one brain region to the next has also been reinforced by cell models  and neurWhile white matter involvement is a prominent feature in neuroimaging investigations of the ALS brain and substantiates the idea of spread along these tracts, to our knowledge no study has tried to verify this concept by looking for the presence of pathology in the core white matter regions implicated. The primary objective of this investigation was to identify pathological evidence of transmission along axonal pathways by looking for pTDP-43 oligodendrocyte pathology in regions implicated by neuroimaging, namely the corticospinal tract in the posterior limb of the internal capsule, the corpus callosum and the cingulum bundle . We alson = 21 males, n = 13 females, age range = 47-81 years) and were matched for age and sex to controls with no evidence of a neurological or neuropathological disease . ALS cases had variable deficits at disease onset, including upper limb onset (n = 11), lower limb onset (n = 14) and bulbar onset (n = 9), but these subsets did not differ in age at onset, age at death or disease duration  was taken from the hemisphere contralateral to the side first affected clinically, in 4 cases (12 %) the sampled region was ipsilateral to the first affected side and in 11 cases (32 %) laterality of onset was bilateral or unknown. In all but three cases, validation of grey matter disease staging was performed using the following recommended blocks [ % was taThe following regions implicated in the neuroimaging literature –10 were Validation of the ALS neuropathological staging scheme was performed in all but three cases by assessing the presence (+) or absence (−) of pTDP-43 pathology in the regions listed above. Based on the regional involvement outlined in Table The severity of Betz cell loss and pTDP-43 pathology  was also evaluated. For Betz cell loss, the motor cortex from 32 the cases was assessed in sections taken from 3–5 consecutive blocks by an experienced neuropathologist, and the number of healthy-looking, normal-sized Betz cells in the lower half of the motor strip in each section was graded from 0 (no Betz cells) to 3 . The scores from each section were averaged to produce a final grade for each case.For pTDP-43 severity, the densest region of pTDP-43 pathology in the grey and white matter of 31 cases was independently graded under a 20x objective using a semi-quantitative scoring system: 0- pathology absent; 1- sparse pathology with no more than 5 inclusions in the entire region; 2- mild pathology with on average 1–5 inclusions in the densest region; 3- moderate pathology with an average of 6–10 inclusions in the densest region; 4- severe pathology with an average of 11 or more inclusions in the densest region  revealed <8 % difference between two investigators.Double-labelling immunofluorescence was performed using antibodies for ALS neuropathology  and oligodendroglia   to confiχ2 analyses performed to determine relationships between clinical and pathological variables. p <0.05 was considered statistically significant.All statistical analysis was performed using SPSS software . Means and standard deviations are shown. Kruskal-Wallis and Mann–Whitney U statistics were used to determine differences between groups and Spearman rank correlations and As expected, all ALS cases were immunopositive for pTDP-43 pathology in one or more of the grey matter regions examined: i.e. the motor cortex, brainstem, sensory cortex, striatum and hippocampus see Fig. . As expeIn the motor cortex, pTDP-43 immunopositive neuronal cytoplasmic inclusions Fig. , glial cThe distribution of ALS cases across the neuropathological stages is outlined in Table The severity of Betz cell loss was variable across all stages and did not influence the severity of pTDP-43 pathology in the motor cortex. Correlations revealed no relationship between the loss of Betz cells and disease stage or the severity of pTDP-43 pathology  with the grey matter having more severe pTDP-43 pathology on average . While the severity of pTDP-43 pathology in the motor cortex and the underlying white matter did appear to increase with stage, the stages themselves did not appear to reflect the same clinical course of disease for all groups (see below).The severity of pathology in the motor cortex Fig.  and its age Fig. . A signin = 6), double-labelling immunofluorescence was performed to confirm that the pTDP-43-immunoreactive aggregates observed in the motor cortex and underlying white matter were indeed mainly in neurons and oligodendrocytes. Double labelling with the oligodendrocyte specific p25α antibody showed pTDP-43-immunoreactive inclusions either surrounding oligodendroglial nuclei . However, the ALS cases with the greatest spread of pathology (Stage 4) were significantly older at onset and had short disease duration, suggesting a difference between this group and other disease stages. Further exploration of these findings is warranted, especially in ALS cases with co-existing dementia as such cases were excluded from this study.The present study validates the neuropathological staging scheme and confirms that regional assessment of pTDP-43 pathology allows for the identification of four specific stages as described previously . Our dat


The high-quality graphene sheets obtained in this work make them suitable for application in many fields such as energy-storage materials and polymer composites.We report an effective method for producing graphene sheets using solvothermal-assisted exfoliation of graphite in a mixed solvent of toluene and oleylamine. The mixed solvent of toluene and oleylamine produces higher yield of graphene than its constituents, oleylamine and toluene. The oleylamine molecules with its long chain enwrap the graphene sheets efficiently, while toluene helps the oleylamine molecules become more flexible and easily intercalate into the edge of graphite. The prepared graphene sheets have a high quality, and the concentration of graphene in the dispersion is as high as 0.128 mg mL The obtained graphene product was dispersed in NMP (30 mL) for UV-visible measurements. By measuring the absorbance of graphene dispersion at 660 nm, the concentration of the exfoliated graphene dispersion was determined from the Lambert-Beer law, using graphene ,23. Rama−1. Thermogravimetric analysis (TGA) was conducted in nitrogen atmosphere at a heating rate of 10°C/min using a TA Hi-Res TGA 2950 thermogravimetric analyzer . X-ray photoelectron spectroscopy (XPS) measurement was performed on an ESCALAB 250Xi photoelectron spectrometer  with Al Kα X-ray radiation as the X-ray source for excitation.Fourier transform infrared (FTIR) spectra were recorded on a FTIR spectrometer  at wavenumbers of 400 to 4,000 cmThe exfoliation of graphite in a mixed solvent using a solvothermal process is depicted in Figure A representative monolayer graphene sheet is shown in Figure The thickness of the prepared graphene sheets was measured by AFM. Figure −1 when the volume ratio of oleylamine/toluene is 5, which is much higher than the reported value (0.01 mg mL−1) for a solvent of NMP [−1), and toluene (1.14 × 10−3 mg mL−1).The concentration of the graphene product at various volume ratios of toluene to oleylamine is shown in Figure t of NMP . This vaDue to the strong ionic interactions between strong acid and oleylamine, the oleylamine molecules readily intercalate into the graphite layers at high temperature and pressure in the solvothermal process. Moreover, with its long chain, oleylamine can prevent the re-aggregation of the graphene sheets effectively, making the graphene suspension more stable.−2 were suggested for the dispersion of carbon nanotubes and graphene [−2, which is lower that the suggested surface tension for the exfoliation of graphite. In view of surface tension, oleylamine and toluene do not seem to be good solvents for the exfoliation of graphite. However, under solvothermal conditions, the oleylamine molecules readily intercalate into the graphite layers, which facilitates the exfoliation of graphite. The addition of toluene into oleylamine makes the oleylamine molecule more flexible, thus increasing the effectiveness of the exfoliation process. Because toluene alone can poorly disperse graphene, the graphene concentration decreases as the toluene content in the mixed solvent increases, i.e., the volume ratio of oleylamine to toluene decreases.For successful exfoliation of graphite, it is necessary to overcome the van der Waals attractions between adjacent graphite layers. One method to reduce the strength of the van der Waals attractions is liquid immersion. By matching the refractive indices of the material and the solvents, the potential energy between adjacent layers which is given by the dispersive London interactions may approach 0. Based on this criterion, solvents with a surface tension of 40 to 50 mJmgraphene ,27. The −1, the G-band at approximately 1,580 cm−1, and the 2D-band at approximately 2,700 cm−1 in both Raman spectra of graphite and graphene product. The D′-band at approximately 1,620 cm−1 is observed in the Raman spectrum of graphene product [ID/ID′) is found to be 1.14. A low value of ID/ID′ indicates that the defects are on-site defects, which describe out-of-plane atoms bonded to carbon atoms  [ID′/IG) is 0.09, indicating that the defects are mostly on sp3 sites, because in the same defect concentration, ID′/IG is higher for vacancies than sp3 sites [D/IG) is found to be 0.11. This ratio is much lower than that of chemically or thermally reduced graphene oxide (approximately 1.2 to 1.5) and graphene prepared by other exfoliation methods, further demonstrating that our graphene product contains a low amount of defects [Raman spectra of the prepared graphene sheets are shown in Figure  product . Low D-bization) . Moreovep3 sites . The int defects -32. An e defects . This in defects ,25,28.Fi−1 is attributed to O-H stretching vibration of adsorbed water molecules and structural OH groups, and a peak at approximately 1,647 cm−1 is ascribed to C=C bending vibrations. Peaks at approximately 1,525 cm−1 reflect the skeletal vibration of graphene [−1 and 2,850 cm−1 which are attributed to stretching of methyl group in oleylamine [−1 which may be attributed to NH2 bending mode [Figure graphene . It is oeylamine -37 and ting mode  indicatiFigure 2) and the second loss around 400°C to 500°C may be attributed to the loss of carboxyl (C=O) and carboxylic groups (O-C=O) [TGA results Figure  reveal t (O-C=O) ,40. The XPS analysis was performed to monitor changes of the structural and chemical composition of the sample during the preparation process. Figure −1 at a volume ratio of oleylamine and toluene of 5. This result is comparable to or higher than previously reported values. An oleylamine molecule with its long chain can intercalate into the edge of graphite during solvothermal process and also wrap the graphene sheets. The addition of toluene, a poor solvent for graphene dispersion, into oleylamine helps oleylamine become more flexible and thus significantly improves the production yield of graphene. High-quality graphene sheets prepared in this work may find their application in many areas from energy-storage materials to polymer composites.In conclusion, we have demonstrated an effective and efficient approach to preparing high-concentration graphene dispersion by solvothermal exfoliation of graphite in a mixed solvent of toluene and oleylamine. The prepared graphene dispersion contains mono or few-layer graphene sheets with a low amount of defects. The graphene concentration in the dispersion is as high as 0.128 mg mL


The prepared LVO NPs-GNs composites displayed high performance as an cathode material for lithium-ion battery, including high reversible lithium storage capacity (237 mA h g−1 after 200 cycles), high Coulombic efficiency (about 98%), excellent cycling stability and high rate capability . Very significantly, the preparation method employed can be easily adapted and may opens the door to complex hybrid materials design and engineering with graphene for advanced energy storage.Lack of high-performance cathode materials has become the major barriers to lithium-ion battery applications in advanced communication equipment and electric vehicles. In this paper, we report a versatile interfacial reaction strategy, which is based on the idea of space confinement, for the synthesis of ultradispersed LiV However, it was also reported that for amorphous one, a maximum amount of 4.5Li+ (ca. 419 mAh g−1) could be demonstrated3O8, more organized arrangements at the subunit level facilitate the inclusion of more lithium ions per unit cell3O8) in lithium-ion batteries are limited by poor electron transport, slow Li-ion diffusion in electrodes, and suffered from fragile surface properties at the interface of electrode/electrolyte at high charge-discharge rates203O8-based materials, such as optimizing particle size22242526−1 have rarely been reported for LiV3O8 cathodes.With the advantages of high energy density, long lifespan and environmental benignity, lithium-ion batteries (LIBs) have become the predominant power source for applications in electric vehicles (EVs), and renewable energy storage in smart grids12345678910Li+ ca. 4 mAh g−1 2 g−1)282930313234363741423O8, which is a promising cathode materials for LIBs.Graphene (G), a monolayer of carbon atoms arranged in a honeycomb network, is one of the most favorable carbonaceous materials for constructing functional composites and/or hybrids because of its unique 2D nanostructure, excellent electron conductivity, good chemical stability, and very high theoretical surface area (2600 m3O8 nanoparticles (~10 nm) and strong coupling on graphene nanosheets (denoted as LVO NPs-GNs) with an unprecedented degree of control on the precise separation and manipulation of nanoparticles nucleation, growth, anchoring, and crystallization on graphene oxide (GO) in a water-in-oil emulsion system over free growth in solution. For comparison LiV3O8 particles were freely grown on graphene sheets in solution via a traditional sol-gel method (denoted as SG-LVO-GNs). Such LVO NPs-GNs composites with the small particle size and uniform distribution of LVO NPs could be controlled with good reproducibility, and anchoring firmly on the GNs is advantageous for inhibiting aggregation and offers a direct short pathway for Li+ diffusion, which are beneficial for high capacity and rate capability. Specifically, this well LVO NPs-GNs composites is able to deliver high reversible capacities with superlative cyclic capacity retention at different current rates for prolonged cycling, and exhibit excellent high-rate performance at a current density as high as 6 A g−1 as an cathode material for LIBs. Very significantly, this facile method may offer an attractive alternative approach for preparation of the graphene-based composites as high-performance electrodes for lithium-ion batteries.Herein, we report a versatile interfacial reaction strategy, which is based on the idea of space confinement, for the synthesis of ultradispersed LiVIn this versatile interfacial reaction design strategy, the unprecedented control of the hybrid materials is achieved by the rational separation and precise manipulation of the synthesis processes  . Firstly3O8. In addition, High-resolution TEM showed the crystal lattice fringes throughout the entire LVO NPs formed on graphene  composites shows the large aggregated nanoparticles and restacked graphene sheets . Diffraction peaks which might appear for graphene are absent, most likely because they are below the limits of detection by XRD or, in the case of the graphene (002) peak, because it is likely to be eclipsed by the LiV3O8 (003) peak. The absence of a reflection peak at approximately 11° indicates that the GO cannot be distinguished, consistent with full or partial reduction to graphene. Raman spectroscopy is a non-destructive approach to characterize graphitic materials, in particular to determine the ordered and/or disordered crystal structure of graphene sheets2g phonons of Csp2 atoms−1) and a broad G band (1590 cm−1) are observed in both samplesD/IG) reflects the graphitization degree of carbonaceous materials and the defect densityD/IG for LVO NPs-GNs (1.37) is much larger than that for GNs (1.26), showing the transformation of graphene sheets from graphene oxide sheets after the thermal treatment. The intensity of the characteristic peak of the D band is slightly stronger than that of the G band, indicating the existence of graphene in the composites. Thermogravimetric analysis (TGA) was employed to determine the amount of graphene in the LVO NPs-GNs (2 g−1 is obtained (Powder X-ray diffraction (XRD) experiments were carried out to reveal the crystallographic phases of the final product, with the result shown in  NPs-GNs . It is iobtained , ESI†. S−1 observed on LVO NCs-GNs at 0.1 A g−1 based on the mass of the active material LVO, which is much higher than that of LVO NCs (212 mA h g−1). This is considered to be because the ultrathin graphene nanosheets act as conducting routes between the LVO NPs, resulting in significantly reduced contact resistance. Remarkably, the reversible capacity of LVO NPs-GNs is still stable at 237 mA h g−1 even after 200 cycles, while the reversible capacities of LVO NPs gradually reduce to 138 mA h g−1  measurements . Furthermore, the interconnected graphene network structure provides a conductive network for electronic transport from LVO NPs within the whole electrode and thus decreases resistance.More exciting results come from the rate performance of LVO NPs-GNs in the urements  were car−1. After 200 cycles, it is clear that the SG-LVO-GNs composites have a lower capacity than that of the LVO NPs-GNs composites. That is because the large aggregated nanoparticles and restacked graphene sheets are produced in solution via a sol-gel method, which leads to lower active sites for lithium storage 49−1, a capacity of 237 mAh g−1 was maintained after 200 cycles. Even at much higher current density of 6 A g−1, a reversible capacity of 55 mAh g−1 was obtained. All of these results demonstrate that the as-prepared LVO NPs-GNs composite encompasses three key advantages of small particle size, uniform dispersion, and strong synergistic coupling effects. Importantly, these results would shed light on the great potential application of cathode materials as high capacity electrode with high rate capability for next generation LIBs. Very significantly, this work opens the door to the rational design and controllable synthesis of useful graphene-based materials for advanced energy storage.In summary, we describe a versatile interfacial reaction strategy, which is based on the idea of space confinement, for the synthesis of LVO NPs-GNs (~10 nm) composites in a W/O emulsion system. It is demonstrated that as the cathode material of LIBs, LVO NPs-GNs composite with the combination of small particle size, uniform dispersion and strong coupling with the graphene sheets render long cycling stability and high rate capability. At a current density of 0.1 A g3 and 46 mL of concentrated H2SO4 were mixed together in an ice bath for 4 h. Then 6.0 g of KMnO4 was added slowly into the solution. Afterwards, the ice bath was removed and the suspension was stirred for another 3 days. Then the suspension was further treated with 200 mL of warm water (~60 °C) and 10 mL of H2O2 (30%). The mixture was centrifuged at 4000 rpm and washed with diluted HCl and water to neutral. Finally, a homogeneous GO aqueous dispersion (1 mg mL−1) was obtained for further use.GO was prepared from graphite flakes by a modified Hummers method52−1) was slowly poured and intensely stirred for 20 min at room temperature resulting in the formation of a golden water-in-oil emulsion. Then 1.8 mmol of NH4VO3 and 2 mmol of H2C2O4 or 1 mmol of LiOH•H2O was added to this golden water-in-oil emulsion while stirring. After 10 min of vigorous agitation, equivalent volumes of two separate microemulsion solutions containing NH4VO3 and H2C2O4 or LiOH•H2O were mixed rapidly. The suspension of the microemulsion were transferred into stainless steel autoclaves and heated at 200 °C for 16 h, followed by cooling to room temperature naturally. After cooled to ambient temperature, the black participates was obtained by centrifugation, and then washed for several times with distilled water. After drying in the vacuum oven at 70 °C overnight, as-synthesized LiV3O8-graphene was annealed at 400 °C for 2 h in an nitrogen flow in order to remove the residual water molecules and functional groups in the rGO, and to improve the crystallinity of LiV3O8 in the obtained composites, which would further improve its electrochemical performance. For comparison, Pure LiV3O8 nanoparticles were also prepared by the similar procedure without any GNs.In a typical experimental procedure, 5.6 g of Cetyltrimethyl Ammonium Bromide (CTAB) was dissolved in a mixture of 10 ml of n-pentanol and 60 ml of n-hexane. Then, 10 ml of GO aqueous dispersion (1 mg mL−1) was slowly poured and intensely stirred for 20 min at room temperature resulting in the formation of a golden transparent solution. Then 1.8 mmol of NH4VO3 and 2 mmol of H2C2O4 or 1 mmol of LiOH•H2O was added to this golden transparent solution while stirring. After 10 min of vigorous agitation, equivalent volumes of two separate solutions containing NH4VO3 and H2C2O4 or LiOH•H2O were mixed rapidly. The suspension of the solution were transferred into stainless steel autoclaves and heated at 200 °C for 16 h, followed by cooling to room temperature naturally. After cooled to ambient temperature, the black participates was obtained by centrifugation, and then washed for several times with distilled water. After drying in the vacuum oven at 70 °C overnight, as-synthesized LiV3O8-graphene was annealed at 400 °C for 2 h in an nitrogen flow in order to remove the residual water molecules and functional groups in the rGO, and to improve the crystallinity of LiV3O8 in the obtained composites, which would further improve its electrochemical performance.In a typical sol-gel experimental procedure, 10 ml of GO aqueous dispersion  and high resolution transmission electron microscopy  with an accelerating voltage of 200 KV. TG analysis was carried out with a TG/DTA6200 instrument. The specific surface area was measured by the Brunauer-Emmett-Teller (BET) method using ASAP2020. Additionally, Raman spectra were recorded at room temperature by employing an InVia Raman spectrometer using 633 nm red laser with 10% intensity to determine the extent of graphitic disorder.The resulting sample was characterized by means of X-ray diffraction  with monochromated Cu K radiation at a scanning rate of 2° min6 dissolved in ethylene carbonate (EC) and dimethyl carbonate (DMC) and diethyl carbonate (DEC) at a volumetric ratio of 1:1:1. The discharge-charge tests were conducted at various rates within a voltage window from 1.5 V to 4.0 V (vs. Li+/Li) on the Battery Testing System (BTS) battery testing system . Electrical impedance spectroscopy (EIS) experiments were carried out on a Parstat 2273 advanced electrochemical systems in the frequency range mainly from 100 kHz to 10 mHz with the a.c. signal amplitude of 5 mV.The LVO NPs-GNs active material powder (~240 mg) was mixed with Super P carbon black and polyvinyldifluoride , with weight ratio of 80:10:10, in N-Methylpyrrolidone (NMP) solvent to produce an electrode slurry. The mass of active materials was calculated at ca. 3.2 mg and integrated into two-electrode CR2025-type coin cells for electrochemical measurements, with LVO NPs-GNs electrode as cathode, metallic lithium foil as anode, porous polypropylene film as separator; electrolyte was 1.0 M LiPFHow to cite this article: Mo, R. et al. Ultradispersed Nanoarchitecture of LiV3O8 Nanoparticle/Reduced Graphene Oxide with High-Capacity and Long-Life Lithium-Ion Battery Cathodes. Sci. Rep. 6, 19843; doi: 10.1038/srep19843 (2016).


In this paper, we report highly conductive, highly flexible, light weight and low cost printed graphene for wireless wearable communications applications. As a proof of concept, printed graphene enabled transmission lines and antennas on paper substrates were designed, fabricated and characterized. To explore its potentials in wearable communications applications, mechanically flexible transmission lines and antennas under various bended cases were experimentally studied. The measurement results demonstrate that the printed graphene can be used for RF signal transmitting, radiating and receiving, which represents some of the essential functionalities of RF signal processing in wireless wearable communications systems. Furthermore, the printed graphene can be processed at low temperature so that it is compatible with heat-sensitive flexible materials like papers and textiles. This work brings a step closer to the prospect to implement graphene enabled low cost and environmentally friendly wireless wearable communications systems in the near future. Wireless wearable communications is a field of increasing research interest due to the numerous potentials offered in areas such as healthcare and fitness monitoring145911However, graphene, the allotrope of carbon nanotube, is a very promising material for wireless wearable communications applications owing to its high conductivity and unique properties5202224However, even though profound progress has been made in graphene active devices, the pace of developing graphene passive RF components has far lagged behind. This is because, in spite of graphene’s high conductivity, both exfoliated and CVD  graphene sheets have very high surface resistance, hindering their applications in RF passive components27293031294 S/m, which is almost double of 2.5 × 104 S/m from previously reported RGO (reduced graphene oxide) with binder and 10 times higher than that from binder-free method29We have developed binder-free technique which is not only compatible with heat-sensitive substrates like papers and textiles, but also offers high conductivity and mechanical flexibilityThe RF passive components in this paper are made of printed graphene. Here we briefly introduce the preparation of printed graphene, and the details are included in the Method sectionThe conductivity and surface resistance of the printed graphene under various compression ratios (the compression ratio is defined as the ratio of the thickness decrement of compressed sample over un-compressed sample thickness) are measured, as shown in TLs are basic structures designated to carry signals and are essential for RF circuits, or indeed any electronic cirucitsThe performance of a TL is mainly determined by material and geometrical parameters such as material losses, substrate material dielectric constant, line gaps, signal line thickness and etc. The insert in The scattering parameters of these lines are measured using Agilent E5071B VNA See  and propα and β are attenuation constant and phase constant, respectively. To eliminate the effect of impedance mismatch on analyzing conductor loss, absorption attenuation, which is defined as the ratio of power entered into the input port of the network over the output power of the network, is calculated bywhere The attenuation is unitized to per Moreover, the superior flexibility of the printed graphene enabled TLs is experimentally verified with the lines of Antenna is used to send and receive RF signals in communications systems. For wearable communications systems, both mechanical flexibility and effective radiation are demanded. For the first time, effective radiation of printed graphene enabled flexible and wearable antenna is experimentally demonstrated in communication frequency bands, such as mobile cellular and WiFi spectrums. 11 at 1.97 GHz is −18.7 dB, and another peak is at 3.26 GHz with −19.2 dB, revealing good impedance matching. The reflection coefficient is under −8 dB from 1.73 GHz to 3.77 GHz, which covers the bands for Wi-Fi, Bluetooth, WLAN  and mobile cellular communications. The maximum gain is 0.2 dBi at 1.92 GHz and above −1 dBi from 1.82 GHz to 3.72 GHz, demonstrating an effective radiation from the printed graphene antenna to the free space. With comparison of reflection coefficients corresponding to different bending cases, it can be seen that the reflection coefficients are not sensitive to the bending and do not vary much. The impedance matching points are almost unchanged. However, the antenna gain changes, especially at higher frequency region. This is because the antenna gain is determined by current distribution on the antenna. When the antenna is bended, the current distribution will be altered, leading to variation on antenna gain performances. Despite that gain at higher frequency band around 3.26 GHz degrades visibly with increasing bending, the gain at lower band around 1.9 GHz to 2.2 GHz has much less variations. This frequency band is where wireless wearable communications systems operate. The experimental data here demonstrate that even when the printed graphene antenna is bended, the radiation at this this frequency band can still be effective.The reflection coefficients of the antenna under these four different bending cases were measured using VNA (Agilent E5071B), and the gain was obtained using three-antenna methodThe corresponded radiation patterns under cases (a)–(d) at 1.97 GHz in elevation plane were also measured using antenna measurement system . The data were recorded for every 10 degree rotation and shown in With the aforementioned verification for the flexibility and efficient radiation of the printed graphene enabled antenna, here we go a step further to prove its potentials in wireless wearable communications systems by presenting a real life scenario shown in 10We have presented highly conductive and flexible printed graphene TLs and antennas using graphene nanoflakes aiming for wireless wearable communications applications. The feasibility of using printed graphene to transmit/receive RF signals through wires and wirelessly has been demonstrated experimentally. The superior flexibility of the printed graphene enabled TLs and antennas has been fully verified with measurements under different bending and twisting cases. An on-body signal transmission on mannequin has been also presented by using printed graphene antennas conformed to the model’s arms for radiating and receiving RF signals wirelessly. It is clearly evident that the sound mechanical flexibility and effective radiation of the printed graphene enabled antennas have successfully facilitated the on-body wireless communications. This work has unambiguously proved that printed graphene can bring transformative change to the formation of RF passive components such as TLs and antennas for wearable applications. Furthermore, the fabrication process is simple and low cost and thus suitable for commercial mass production. Combined with other profound advantages in lightweight, mechanical flexibility and environmental friendliness, printed graphene can be ideal for low cost consumable wearable electronics.Graphene nanoflakes were dispersed in N-Methyl-2-pyrrolidone (NMP) solvent to form a uniform 10 wt% graphene ink, i.e. Grat-Ink 102E. Less than 1 wt % of non-ionic polymer-type surfactants was contained in the ink. The presence of the surfactants improve the dispersion of graphene flakes and viscosity helping in deposition of a uniform film. The Grat-Ink 102E, prepared as described above, was used to print the samples in this study. Conventional paper was used as the substrate, and the patterns of the samples were printed by 150 mesh stainless-steel screen via a manual laboratory screen-printing table. They were dried at 100 °C for 10 minutes. Further a rolling compression procedure was followed using compression roller  to obtain highly dense graphene laminates. The different compression ratio and thickness of samples are controlled by adjusting the space between two rollers. High reproducibility can be guaranteed when roller distance is fixed during operation. The sheet resistance of the graphene laminate pattern was measured by the 4-point probe . The thicknesses of un-compressed and compressed graphene patterns were measured with digital thickness gauge . A total of 10 measurements at different spots were carried out to obtain the average value of each sample.How to cite this article: Huang, X. et al. Highly Flexible and Conductive Printed Graphene for Wireless Wearable Communications Applications. Sci. Rep.5, 18298; doi: 10.1038/srep18298 (2015).


Direct deposition of graphene layers on the flexible glass fiber surface to form the three-dimensional (3D) core-shell structures is offered using a two-heating reactor chemical vapor deposition system. The two-heating reactor is utilized to offer sufficient, well-proportioned floating C atoms and provide a facile way for low-temperature deposition. Graphene layers, which are controlled by changing the growth time, can be grown on the surface of wire-type glass fiber with the diameter from 30 nm to 120 um. The core-shell graphene/glass fiber deposition mechanism is proposed, suggesting that the 3D graphene films can be deposited on any proper wire-type substrates. These results open a facile way for direct and high-efficiency deposition of the transfer-free graphene layers on the low-temperature dielectric wire-type substrates.81.05.U-; 81.07.-b; 81.15.Gh Graphene has been reported by numerous papers on the growth[2 g-1)[Graphene as typical spe growth-6, propee growth,8, and ae growth-11. In me growth, catalyse growth, batterye growth, and wate growth, a smalle growth-25. Diffe growth,15, carbe growth, graphene growth,16,17,23e growth,25, havee growth, hydrothe growth, laser-be growth, and CVDe growth approache growth. The rese growth. The pere growth. Three-d[2 g-1), is also[2 g-1),24,25. H2 strip of copper foils serving on the catalyst for the thermal dissociation of CH4 was located in higher constant-temperature zone , and the glass fiber membrane substrates  were spaced in the lower constant-temperature zone (600°C). Next, the horizontal quartz tube was pumped to 1.0 × 10-6 Torr and heated in the meanwhile. When the temperature reached 300°C, the Cu foil surrounding the tube was annealed in the flow of H2 and Ar (100 sccm/500 sccm) to remove the copper oxide. After another 30 min of annealing at 1,000°C, CH4 (50 sccm) and H2 (50 sccm) were introduced for 10 to 120 min of growth. Finally, the furnace was cooled down to the ambient temperature rapidly by simply opening the furnace.As shown in Figure Following growth, the morphology of the sample was characterized with scanning electron microscope  and transmission electron microscope . Raman spectra were obtained with a HORIBA HR800 Raman microscopy system  (laser wavelength 473 nm and laser spot size about 0.5 mm). The resistance of the sample was measured by depositing the silver electrode on the surface.-1. For the Raman spectrum of the sample grown for 10 min, The I2D/IG intensity ratio is approximately 1.1, and the full width at half maximum (FWHM) of 2D band is approximately 45 cm-1, which represents one to two layers of graphene film[I2D/IG intensity ratio is approximately 0.5, and the full width at half maximum (FWHM) of 2D band is approximately 55 cm-1, which represents three to five layers of graphene film[Figure ene film. For theene film. Compareene film. In partIt is possible to investigate the state of the graphene by transferring it to a small holey copper grid using TEM. The HR-TEM image  growth is necessary due to the lower melting point of the glass fiber, which can be obtained by the revised CVD system with the two-heating reactor. The mechanism of synthesis of core-shell graphene/glass fiber structures by using such revised CVD system has been discussed here. The higher constant-temperature zone offers enough power for the dissociation of methane with the assist of copper catalyst, and the lower constant-temperature zone makes that the decomposed carbon atoms deposit readily on the substrate. Meanwhile, the distinct form of the temperature variation effectively controls the regions that the evaporated Cu atoms and the decomposed carbon atoms deposit. The gently declined temperature zone can make the evaporated Cu atoms deposit on the region close to the higher constant-temperature zone. Higher-2 wafer and wire-type fiber substrates, while the grown graphene layers are different, especially after a longer time growth. The plant SiO2 wafer substrate and single-mode fiber  are also used here to deposit graphene film for 120 min in the same CVD process. Figure -1 are also observed in both of the Raman spectra  related to a graphene layer structure is also hardly observed. The I2D/IG intensity ratio is only 0.2, and the full width at half maximum (FWHM) of 2D band is up to approximately 70 cm-1. These results represent that there are many graphene layers and many defects are formed on the wire-type glass fibers.It should be stressed that the graphene film can be grown on the plant SiO2 substrate are predominantly monolayer, due to the growth process is self-limited. As is well known, SiO2 has higher surface energy than after it is covered by graphene. Namely, the cohesion energy between SiO2 and graphene is higher than that of graphene-to-graphene. Therefore, after being covered by a layer of graphene, the carbon species become hard to nucleate on the graphene-covered area due to the relatively weak cohesion energy, refusing to form the second layer[2 wires. The metal elements existed in the SiO2 wires are caused by the formation of the glass membranes. All of the overlaps and defects can be used as the catalyst sites to further grow the graphene layers. From Figure In fact, graphene growth on the plant SiOnd layer. But, on2, SMF, and glass fiber membrane substrate. The excellent electrical properties further demonstrate that high-quality graphene layers can be prepared using such two-heating reactor CVD system in the relatively low temperature. The lower sheet resistance of the glass fiber membrane samples is caused by the more layers of the graphene films.We also measured the sheet resistance (Rs) of the prepared graphene film obtained at room temperature. The calculated average value of the Rs is approximately 700, 300, and 180 Ω/sq for the plant SiOWe have demonstrated the facile low-temperature growth of 3D graphene/glass fiber wire-type structures using a two-heating reactor. The higher constant-temperature zone offers enough power for the dissociation of methane with the assist of copper catalyst, and the lower constant-temperature zone makes that the decomposed carbon atoms deposit readily on the substrate. Graphene layers can be grown on the different diameter wire-type glass fiber surface to form graphene/glass fiber wire-type structures. The morphology and electrical properties of such structures can be controlled by changing the growth time. These results suggest that the 3D graphene films can be deposited on any proper wire-type substrates.The authors declare that they have no competing interests.CY and BM are the corresponding authors and designed the experiments and sample preparations and drafted the manuscript. YX, CZ, ZS, CC, XL, and SJ took part in the sample preparation and characterizations and discussed the results. All authors have read and approved the final manuscript.2Se3, and MoS2. XL works in Lishan College at Shandong Normal University; her research focus is solar materials. SJ and CC are professors in the College of Physics and Electronics at Shandong Normal University. They are M.S. Supervisor. Their main interests include nanomaterials, mode-locked lasers, and laser plasma.BM is a professor in the college of Physics and Electronics at Shandong Normal University, China. He is a Ph.D. supervisor. His main research interests include nanomaterials and laser plasma. CY has graduated from SungKyunKwan University (SKKU), Korea. Currently, he works at Shandong Normal University. His research subject is nanomaterials and their applications. YY, CZ, and ZS are currently doing their Ph.D. at Shandong Normal University. Their research subjects are related to 2D nanomaterials such as graphene, Bi


Background: The Loess Plateau, an ecologically vulnerable region, has long been suffering from serious soil erosion. Revegetation has been implemented to control soil erosion and improve ecosystems in the Loess Plateau region through a series of ecological recovery programs. However, the increasing atmospheric CO2 as a result of human intervention is affecting the climate by global warming, resulting in the greater frequency and intensity of extreme weather events, such as storms that may weaken the effectiveness of revegetation and cause severe soil erosion. Most research to date has evaluated the effectiveness of revegetation on soil properties and soil erosion of different land use or vegetation types. Here, we study the effect of revegetation on soil organic carbon (SOC) storage and erosion-induced carbon loss related to different plant communities, particularly under extreme rainstorm events. Materials and methods: The erosion-pin method was used to quantify soil erosion, and soil samples were taken at soil depths of 0–5 cm, 5–10 cm and 10–20 cm to determine the SOC content for 13 typical hillside revegetation communities in the year of 2013, which had the highest rainfall with broad range, long duration and high intensity since 1945, in the Yanhe watershed. Results and discussion: The SOC concentrations of all plant communities increased with soil depth when compared with slope cropland, and significant increases (p < 0.05) were observed for most shrub and forest communities, particularly for natural ones. Taking the natural secondary forest community as reference , the relative soil loss and SOC loss of the other 12 plant communities in 2013 ranged from 1.5 to 9.4 and 0.30 to 1.73, respectively. Natural shrub and forest communities showed greater resistance to rainstorm erosion than grassland communities. The natural grassland communities with lower SOC content produced lower SOC loss even with higher soil loss, natural secondary forest communities produced higher SOC loss, primarily because of their higher SOC content, and the artificial R. pseudoacacia community with greater soil loss produced higher SOC loss. Conclusions: These results indicate that natural revegetation is more effective in enhancing SOC storage and reducing soil erosion than artificial vegetative recovery on hillsides. However, natural secondary forest communities, with higher SOC content and storage capacity, may also contribute to larger SOC loss under extreme rainstorms. Soil, the largest pool of terrestrial organic carbon in the biosphere and approximately 3.3 times the size of the atmospheric pool and 4.5 times the size of the biotic pool ,2, playsThe Chinese Loess Plateau has long experienced serious soil erosion, and severe soil and water loss has led to widespread land degradation . Land usConversion of land use to agriculture has many potential implications for the mobilization and export of SOC . Floodini.e., trees for soil and water conservation, such as Robinia pseudoacacia, Pinus tabuliformis, Caragana intermedia, and Hippophae rhamnoides) and “economic forests”  [Artemisia scoparia, Lespedeza davurica, Artemisia gmelinii, Bothriochloa ischaemun, Sophora viciifolia, and Quercus liaotungensis, respectively [Revegetation probably enhances the carbon storage capacity of terrestrial ecosystems on the Loess Plateau ,28. The ulgaris) . Howeverulgaris) ,32,33,34ulgaris) ,36. In tectively ,38. Althectively ,40, it iectively . Owing tectively , correspectively ,44 or thectively ,46,47. HThus, the objectives of this study were to examine the effects of revegetation on soil organic carbon storage and carbon losses caused by soil erosion on hillsides in response to extreme rainstorm events in the hill and gully area of the Loess Plateau by analyzing: (1) changes in soil organic carbon content and capacity for soil carbon storage; and (2) soil erosion and erosion-induced carbon loss of different plant communities. The results of this study could provide references for strategies towards the optimization of vegetation restoration and climate change mitigation in the Loess Plateau region.2 is the primary tributary in the middle reaches of the Yellow River and belongs to the hill-gully region of the Loess Plateau. The climate is semi-arid, with mean annual precipitation of 500 mm (420–540 mm), and mean air temperature of 9.5 °C (8.80 °C to 10.2 °C). The seasonal distribution of precipitation is uneven, characterized by intensive rainfall from July to September that accounts for more than 60% of the annual rainfall. Soils are predominantly loess and have a texture of 64%–73% silt and 17%–20% clay; the loose soils are vulnerable to dispersion and transport [The study area was located in the Yanhe watershed at N 36°23′–37°17′ and E 108°45′–110°28′ . The watransport ,49. Quercus liaotungensis, Pinus tabuliformis, Platycladus orientalis, and Acer buergerianum. The dominant shrub species include Syringa julianae, Sophora viciifolia, Periploca sepium, and Ostryopsis davidiana. And the dominant herb species include Artemisia scoparia, Stipa grandis, Stipa bungeana, Artemisia gmelinii, Artemisia giralaii, Thymus mandshuricus, Bothriochloa ischaemum, Lespedeza davurica, and Carex lanceolata. The primary introduced tree species include Robinia pseudoacacia, Populus simonii, Hippophae rhamnoides, Caragana intermedia, and Salix matsudana. The economic forests are dominated by Malus pumila, Prunus davidiana, and Armeniaca sibirica [.The natural vegetation is composed of grassland, shrub and secondary forest. The dominant tree species include sibirica .Artemisia scoparia (A), Stipa bungeana + Lespedeza davurica (SL), Artemisia gmelinii + Stipa bungeana (AS) and Artemisia gmelinii + Artemisia giralaii+Bothriochloa ischaemum(AAB); two natural shrubland communities of Sophora viciifolia − Artemisia gmelinii + Stipa bungeana (SAS) and Syringa julianae − Carex lanceolata (SC); two natural forestland communities of Quercus liaotungensis − Syringa julianae − Carex lanceolata (QSC) and Acer buergerianum − Syringa julianae − Carex lanceolata (ASC), two artificial shrubland communities of Hippophae rhamnoides − Artemisia gmelinii + Stipa bungeana (HAS) and Caragana intermedia − Artemisia gmelinii + Stipa bungeana (CAS); and three artificial forest communities of Armeniaca sibirica − Artemisia gmelinii + Stipa bungeana (AAS), 6–8 years Robinia pseudoacacia − Artemisia gmelinii + Stipa bungeana (RAS1) and 15 years Robinia pseudoacacia − Artemisia gmelinii + Stipa bungeana (RAS2). Each community had three replicate sites distributed in different sub-watersheds, and three replicates of slope croplands  were used as the reference . Soil bulk density of each plot (3 replicates) was measured collecting soil with a bulk sampler (100 cm3) near the soil sampling points, and comparing the original mass of each soil core with the mass after oven-drying at 105 °C for 24 h. At each site, soil samples were collected with a soil auger  from nine points in an S-shaped pattern that paralleled the slope at depths of 0–5 cm, 5–10 cm and 10–20 cm. The soil samples from the nine points in each depth were mixed, respectively. Live plant materials (roots and shoots) and pebbles from each sample were separated in the laboratory and discarded. All samples were air-dried, crushed, and passed through a 0.15 mm sieve prior to the SOC analysis. SOC was determined by using the oil bath-KjX is the average soil erosion of each site, iD is the average depth (mm) of the nine nails in each plot, iB is the average soil bulk density (g·cm−3) of each plot, 103 is the unit conversion factor, S is the soil erosion (t·km−2·yr−1) of each plant community, SL is the soil organic carbon loss (t·km−2·yr−1) of each plant community, and jP is the average soil surface (0–5 cm) organic carbon percent content (%) of each site; i is the plot number of each site and m is the total number of plots, j is the site number of each plant community and n is the total number of sites.As the topsoil was disturbed and transported once water erosion had taken place, the organic carbon percentage content (%) of 0–5 cm soil layer was used as the base value to calculate soil organic carbon loss. The soil erosion and soil organic carbon loss in different plant communities were calculated using the following equations:Q. liaotungensis − S. julianae − C. lanceolata (QSC), with the lowest soil erosion and the highest soil organic carbon, was used as a reference to calculate relative soil loss and soil organic carbon loss of the other communities. The relative soil loss and soil organic carbon loss in different plant communities were calculated using the following equations:SR and SLR is the relative soil loss and relative soil organic carbon loss, respectively, kS and kSL is the soil erosion and soil organic carbon loss in different plant communities, k represents the 13 plant communities, QSCS and QSCSL is the soil erosion and soil organic carbon loss of the natural forestland community Q. liaotungensis − S. julianae − C. lanceolata (QSC), respectively.As the absolute values were obtained in a year experiencing extraordinary storm events, relative soil loss and soil organic carbon loss values were considered to be more meaningful. Therefore, the natural forestland community p < 0.05. Statistics were run using SPSS 16.0 . Figures were drawn using Sigmaplot 12.0 .A two-way analysis of variance (ANOVA) was used to examine the effects of plant community and soil depth on soil organic carbon content. A one-way ANOVA was used to identify the effects of plant community on relative soil loss and relative soil organic carbon loss. If significant effects were detected with the ANOVA, differences between individual means were tested using the Tukey Honestly Significant Difference (HSD) test at p < 0.05) at all soil depths. The SOC content in each soil layer of the natural secondary forest communities was significantly higher (p < 0.05) than in other natural plant communities. In addition, the SOC content of the AS community was significantly higher (p < 0.05) at each soil depth than in other natural grassland communities, and there was no significant difference between the other natural grassland communities. The SOC content of the natural secondary forest and shrub communities was significantly higher (p < 0.05) than the SOC content of artificial forest and shrub communities, respectively. In addition, the SOC content of each soil layer was not significantly different between artificial forest communities (except for the RAS1) or between artificial shrub communities. The two-way ANOVA indicated that plant community and soil depth had significant effects on SOC content . Compare−1 at 0–5 cm, from 3.89 to 26.71 g·kg−1 at 5–10 cm, and from 2.71 to 18.44 g·kg−1 at 10–20 cm (p < 0.05), but this change was not significant for the grassland communities. SOC content was significantly higher (p < 0.05) in the 0–5 cm soil layer than in the deeper soil layers of the forest community (except for RAS1) and shrub communities (except for the HAS). The SOC content of the different plant communities ranged from 4.86 to 52.89 g·kg10–20 cm . As soilIn July 2013, the Yanhe watershed experienced consecutive heavy rainfalls with broad range, long duration and high intensity. At each meteorological station , the tot−2·yr−1 to 5145 t·km−2·yr−1. The QSC community had the lowest soil loss and was used as a reference to calculate the relative soil loss of the other plant communities. The relative soil loss within the four natural grassland communities ranged from 3.1 to 4.1, and the A community had the lowest resistance to erosion. There was no significant difference in relative soil loss between the two natural shrub communities, which showed a higher resistance to erosion than the grassland communities. Relative soil loss of the secondary forest communities was 1 and 1.5 and showed the greatest efficacy for reducing erosion. In the two artificial shrub communities, relative soil loss was 3 and 3.9. Relative soil loss of the artificial forest communities ranged from 3.4 to 9.4, and the 6–8 years R. pseudoacacia community showed the lowest resistance to erosion among the 13 plant communities  and the AAS community (0.66). No significant difference was found between the two natural forest communities (1.05 and 1). The 15 years R. pseudoacacia community had the highest relative SOC loss between the 13 plant communities  content of all the vegetation types were higher than slope cropland , artificial shrubs (Prunus armniaca) and immature forest plantations (Robinia pseudoacacia). In our study, compared with slope cropland, the SOC content for R. pseudoacacia land was not significantly higher after six to eight years of revegetation, but a significant increase was observed at the soil surface (0–5 cm) after 15 years  also showed increased tendency . Similaret al. , who sho15 years . Lu et a , large areas of slope cropland were converted to trees, shrubs, or grasses within the Loess Plateau region ,58. Planet al.  found thet al. [H. rhamnoides, with a mean canopy cover of 92% and a litter depth 30 mm, is a powerful agent of erosion control during extreme hydrological events . However, H. rhamnoides did not achieve a similar effectiveness in controlling soil erosion in our study, which can be accounted for by the significantly lower canopy cover and litter depth . Natural secondary forest communities, especially the QSC, were most effective at protecting the soil from erosion, which can be unequivocally attributed to the dense canopy structure and the higher litter cover , especially in the 0–5 cm soil layer, and natural vegetative recovery was a more effective pathway for increasing SOC concentration and enhancing SOC storage than artificial vegetative recovery in the Chinese loess hill and gully region. R. pseudoacacia communities, with higher soil loss, produced greater SOC loss; and natural secondary forest communities, with higher carbon-concentrated soils and SOC storage capacity, may produce more SOC loss from water erosion under extreme rainstorm events.Soil erosion and erosion-induced carbon loss is tightly linked with vegetation types under extreme rainstorm events. Grassland communities, with a higher soil loss and a lower SOC content, had less SOC loss; shrub communities were intermediate in SOC content and loss; artificial