Vaccine-hesitant persons who inject drugs are at increased risk for several vaccine-preventable diseases. However, vaccination rates among this population remain low. While syringe services programs (SSPs) are places where persons who inject drugs feel comfortable accessing services, few offer vaccination services. This study describes facilitators and barriers to vaccination at SSPs.We used convenience sampling to conduct semi-structured, qualitative in-depth interviews with 21 SSPs in the USA from June to August 2021. Interview questions asked SSPs about their perceptions, priorities, barriers, facilitators, and the effects of partnerships and policies on vaccine administration. We used deductive thematic analysis to identify the main themes.n = 8) SSPs offered vaccinations, and thirteen (n = 13) did not offer vaccinations. Most SSPs believed offering vaccination services was important, although addressing SSP participants’ immediate needs often took precedence. Staffing, physical space, and logistical issues were the most common barriers to vaccine administration reported by SSPs, followed by SSP participant-related barriers. Facilitators of vaccine administration included access to a tracking system, partnering with agencies or other organizations providing vaccines, and having a licensed vaccination provider on-site. Partnerships provided SSPs opportunities to expand capacity but could also restrict how SSPs operate. Recommended policy changes to facilitate vaccine administration included subsidizing the cost of vaccinations and addressing restrictions around who could administer vaccinations.Eight (Increasing the availability of vaccination services at SSPs requires addressing the varying capacity needs of SSPs, such as tracking systems, licensed vaccinators, and free or low-cost vaccination supplies. While these needs can be met through partnerships and supportive policies, both must consider and reflect cultural competence around the lived experiences of persons who inject drugs. Persons who inject drugs are at increased risk for several vaccine-preventable diseases, including hepatitis A , hepatitDespite elevated risks of viral hepatitis among people who use drugs and the availability of effective vaccines, recent studies documented vaccination rates of 32–51% for hepatitis A and 35–56% for hepatitis B among this population –12. Accen = 105), 44% offered any vaccinations on-site; among those, the most commonly provided vaccines were COVID-19 (91%), hepatitis A (76%), influenza (73%), hepatitis B (70%), and tetanus (57%)  stuff out” (NV-387).Despite being a priority, many SSPs recognized specific organizational challenges to vaccine administration. Capacity and logistical issues were the most common barriers to vaccine administration reported by SSPs, followed by participant-related barriers.“I think, well, one of the things is, is there a nurse available? Because it's not ideal to talk to somebody and counsel them and get them excited about whatever service it is, including vaccinations. And then, "Oops, nobody's here. You have to come back another time" (V-651).Over half the SSPs cited limited capacity as a barrier to vaccine administration. Some capacity issues included not having enough physical space to administer vaccines, inability to store or transport vaccines, and no or limited staff qualified to administer vaccines and complete vaccine-related tasks like data entry, tracking, and follow-up. As one SSP explained, they did not want to advertise a service to participants if no one was available to provide it.“What's been difficult is we've not been able to offer consistency. And I think that's hard. Usually, we like to keep things very consistent, just so our participants know what they can count on” (V-855).Most SSPs we spoke to had only one or two full-time staff. Limited staff created the additional problem of time management. Several SSPs struggled with making time to administer vaccines and the associated tasks, such as assessing participants’ needs, accessing records, providing education, data entry, and addressing participants’ vaccination questions. In addition, SSPs with vaccine programs noted that these challenges often created delays or rescheduling of vaccine events, making it tough to offer vaccination services consistently."Honestly, it's just about getting our participants to sit down and discuss that as a need…So I think the biggest barrier is that we don't have that face-to-face interaction with our participants as much as we would like to" (NV-861).In addition to staffing, many SSPs reported participant-level barriers, including a lack of participant demand for vaccinations and vaccine hesitancy specific to COVID-19 vaccinations, which created challenges for vaccine administration. Several SSPs believed that having more staff would allow them time with participants to stress the importance of vaccinations.We asked the SSPs we interviewed about facilitators for initiating or scaling up vaccination services. Most SSPs not offering vaccine services believe having access to a system to track and look up a participant’s vaccination history would make it easier to offer vaccinations. However, among those SSPs, a couple had concerns about using a vaccine tracking system. For example, one SSP worried about participant acceptance of sharing personally identifiable information linking them to an SSP. Another SSP was unsure if access to such a system would assist their ability to offer vaccines because of their staff's lack of familiarity with navigating a tracking system.“Having a tracking system would allow us to create a more targeted approach to who would most likely get a vaccine. And it would probably also help us identify clients who have already been vaccinated” (V-198).More than half of the SSPs without vaccination programs said they would use a tracking system to verify which patients were vaccinated and who needed vaccinations. Several SSPs said they would use this information to tailor their approaches and create better messaging for participants around vaccinations and other medical needs. One SSP believed such a system would allow them to keep track of some aspects of patients' medical histories, especially those who are unstably housed and often have incomplete or nonexistent medical records.Regarding tracking, we asked SSPs if they believed clients would be concerned about their anonymity. A few thought it could be problematic if the client felt their vaccine record would link them back to an SSP. However, most SSPs did not believe concerns over anonymity to be a substantial barrier, especially if the SSP offered or was co-located with a place that offered other services.Half of the SSPs without vaccination programs thought partnering with agencies or other organizations currently providing vaccines would help make it easier to start offering vaccinations to their participants. Most SSPs who mentioned partnerships wanted to partner with a medical facility, community clinic, or another SSP. The remaining SSPs desired to partner with local health departments."I don't think [our staff is] super comfortable talking about vaccinations or immunizations with our clients just because they don't know much about them… It scares people to talk about it if they're not nurses or don't give the vaccine. So, if they had more information on how to provide or offer them, they could maybe do that" (V-830).About a third of SSPs without vaccination programs believed having a licensed healthcare provider on-site would allow them to initiate a vaccination program. A similar number of SSPs said funding for advertising, health promotion, and infrastructure  would facilitate their ability to start a vaccination program. Other facilitators included staff training and staff buy-in.For SSPs currently offering vaccine services, most thoughts increased capacity  would make it easier to scale up their vaccination programs. A few SSPs offering vaccination services mentioned funding to promote vaccination services to the community better and incentivize participants. Example incentives included food, money for transportation, and essential need items . Staff training to address vaccine hesitancy among participants and community education to combat stigma around SSPs were also described as facilitators.[The health department] provides all the supplies, the syringes, and safe-to-use supplies. And then, we supply the supplies they cannot purchase with their money. Because we aren't a health department, we can take a few more risks to distribute things like glass pipes or bleach that they can't. So, we come together to provide the items at the SSP and services" (V-911).Most non-health department SSPs we spoke to have a relationship with their local health department; however, their partnerships ranged from nominal, such as a referral source for participants, to extensive. Almost all SSPs with vaccination programs obtained their vaccines and vaccine-related supplies from the health department. The benefits of partnering with local health departments included access to funding, and physical storage space, staff with clinical training, referrals to needed services, and training opportunities for their staff. Several SSPs explained how their partnerships with the health department allowed them to construct a network of services for their participants."[F]inding the time to network is very difficult to be able to, 'Hey, this is what we do. We're wondering if we could partner with you in some way'. It's time-consuming. And as far as what we would need is maybe some soft introductions, even if it's just an email introduction to get something going without us having to do our whole spiel, that would be great" (NV-232).One SSP noted that while they were aware of the benefits of partnering with local health departments, some smaller, low-capacity SSPs lack the time and ability to establish these partnerships."For the most part, [our relationship with the local health department] is just surface because of what my SSP stands for and why we haven't jumped on some public health grants. First, we are very concerned about harm reduction being co-opted and medicalized. Those with grassroots organizations must ensure that those working in SSPs have lived experience. They know the stigma of different cultural aspects and are familiar with the drug culture and our participants" (NV-374).Despite the stated benefits of partnering with local health departments, a few SSPs discussed their concerns with partnering. For example, several SSPs expressed concerns about partnering staff lacking the cultural competence to work with SSP participants and their potential to further stigmatize or mistreat them because of their drug use."We used to [partner with the local health department], but not so much anymore. The health director changed. And then the sheriff changed, there was someone at the health department who did not like people who use drugs and that caused animosity between her and me, and it ended up dissolving" (NV-561).Other SSPs were leery that health departments would impose rules around what and how services are offered. One SSP shared how their funding, services provided, and policies were affected by changing administration politics.“I think just the reimbursement, whatever it is, the Medicaid or Medicare, or both, reimbursement for hepatitis A is a challenge because we only have a limited supply of those free Hep-A vaccines” (V-651).During our interviews, we asked SSPs if there are local or state policies or legislation that impacted their ability to provide vaccinations. Almost half of the SSPs identified jurisdiction-specific policies requiring that only a licensed healthcare provider could administer vaccines as a barrier to initiating or scaling up their vaccine programs. One SSP explained how the lack of Medicaid reimbursement for hepatitis A vaccines presented challenges for participants with Medicaid coverage.“I wouldn't say that any policies make it difficult, especially not at the state level. Locally, I would say our biggest barrier is more attitude towards the SSP program, [and] participants in the SSP program that make it difficult for us to more publicly advertise kind of the services that we're offering” (V-198).Several SSPs clarified that negative community attitudes toward SSPs, not policies, limited their ability to advertise for their vaccination program and other services they offered.“I think just offering vaccinations for free to all individuals would be the easiest and the most meaningful legislation. It's difficult sometimes to get vaccines to people if they don't fall in certain categories” (V-830).A few SSPs proposed policy or legislative changes to support their vaccination programs. More than one SSP suggested eliminating user fees for all adult vaccinations.The remaining proposed policy or legislative changes included removing barriers around who could administer vaccines and getting full reimbursement for hepatitis A vaccines from Medicaid.SSPs are an essential public health partner for reducing vaccine-preventable diseases among persons who inject drugs. These qualitative interviews with 21 US SSPs identified limited personnel and space capacity, logistical issues, and participant concerns as barriers to vaccination programs at SSPs. Trusted partnerships with organizations providing vaccines, availability of an on-site, licensed vaccinator, and access to a vaccination tracking system were identified as facilitators of vaccination programs at SSPs. Overall, SSPs supported vaccinations and recognized the importance of vaccinations for improving the health of persons who inject drugs; however, SSPs face fundamental challenges in initiating vaccination services for participants. Our interview project identified three opportunities for public health partners to support SSPs in starting or scaling up vaccination services—building capacity for staffing, space, and equipment, providing access to immunization information systems, and enhancing culturally competent partnerships.To expand vaccination services and provide consistent vaccination access, SSPs need support to increase staffing, space, and equipment capacity. Efforts to increase the number of SSP staff, hire staff who can administer vaccinations, and enable SSPs to provide vaccinations on-site would help make staff more available to engage in vaccine conversations. To address the challenges of hiring licensed vaccinators, jurisdictions could review local regulations and expand the types of providers eligible to administer vaccinations with appropriate training and supervision. Health departments can share existing vaccination training resources with SSPs, which would make it easier for SSP staff to engage participants in vaccine conversations. Addressing participants’ competing priorities by offering food, transportation, or housing resources and reducing the steps needed to receive vaccination would help participants engage in meaningful vaccine conversations. However, understanding the feasibility and effectiveness of direct incentives, like financial incentives, deserves further study. CDC supports SSPs through cooperative agreements to support –31 COVIDOur findings highlighted heterogeneity in the provision of on-site vaccination services. Accessibility of vaccinations depended on the hours of operation, the number of staff, and whether licensed vaccinator staff were available part-time or full-time. SSPs noted the importance of consistency when offering services, including vaccination services. Provided with adequate staffing resources, SSPs will also need support to incorporate vaccination screening and services into regular workflows. Providing SSPs with access to immunization information systems (IISs) will assist SSPs in tracking vaccination histories and tailoring vaccination services. Some SSPs described reviewing vaccination status before participant visits or using a cover sheet to remind providers to ask about vaccination. Improving access to IISs could help SSPs use limited staff time and improve consistency in offering vaccinations.Most SSPs used partnerships to create a network of services for their participants but also for their sustainability and growth, providing many SSPs with funding, staff, physical space, training, supplies, and capacity building. The trusted relationship between SSP staff and participants is key to increasing vaccine acceptance among persons who inject drugs. Expanding partnerships between SSPs and public health and healthcare agencies should not compromise trusted relationships between SSPs and their participants. Studies of SSPs  during tThis report is subject to limitations. The qualitative interviews were conducted during the first 12 months of COVID-19 vaccine availability; recent COVID-19 experiences informed many responses. Although we interviewed a mixture of SSPs with and without vaccination services and from a wide geographic range, the perspectives in the interviews might not be representative of all SSPs in the USA.Federal, state, and local public health partners can support SSPs to initiate or scale up vaccination services for persons who inject drugs by supporting the expansion of SSP capacity, providing access to immunization information systems, supporting operational environments conducive to quality partnerships, and addressing the stigma around injection drug use.Despite the great need for access to vaccinations among persons who inject drugs, only a few SSPs offer vaccinations on-site. We found that increasing the availability of vaccination services at SSPs requires addressing the varying capacity needs of SSPs, such as tracking systems, licensed vaccinators, and free or low-cost vaccination supplies. Many of these needs can be met through SSPs developing partnerships with existing vaccine providers and supportive policies that lower barriers for SSPs wanting to provide vaccination services. Critical for both success and sustainability, partnerships and policies must consider and reflect cultural competence around the lived experiences of persons who inject drugs.


However, in addition to being costly and time-consuming, existing strategies for synthesizing sulfides/graphene composites often involve complicated procedures. It is therefore essential to develop a simple yet scalable pathway to construct sulfide/graphene composites for practical applications. Here, we highlight a one-step, template-free, high-throughput “self-bubbling” method for producing MoS2/graphene composites, which is suitable for large-scale production of sulfide/graphene composites. The final product featured MoS2 nanoflakes distributed in three-dimensional macroporous monolithic graphene. Moreover, this unique MoS2/graphene composite achieved remarkable electrochemical performance when being applied to Na-ion battery anodes; namely, excellent cycling stability (474 mA h g−1 at 0.1 A g−1 after 100 cycles) and high rate capability (406 mA h g−1 at 0.25 A g−1 and 359 mA h g−1 at 0.5 A g−1). This self-bubbling approach should be applicable to delivering other graphene-based composites for emerging applications such as energy storage, catalysis, and sensing.Layered metal sulfides (MoS 2 composites for improved performances in sodium-ion batteries.A single-step, template-free, high-throughput synthesis method is developed to produce graphene/MoS Unfortunately, due to the large volume change and/or the sluggish kinetics during charge/discharge cycles, these materials delivered either low reversible capacity or poor cyclability.12 Consequently, layered metal sulfides  have also been explored as anode materials in NIBs due to their unique structural characteristics.13 For example, molybdenum sulfide (MoS2), stemming from its large interlayer spacing  and high capacity for hosting foreign species, has been recently highlighted as a possible candidate for anode material in NIBs.14–19 According to the intercalation and conversion reaction between one MoS2 molecule and four Na+, the theoretical capacity of MoS2 is as high as 670 mA h g−1.20Sodium-ion batteries (NIBs) have been proposed as promising alternatives to lithium-ion batteries (LIBs) in the megawatt- and kilowatt-scale energy storage scenarios  in addition to be costly and time-consuming.28 Another issue with existing MoS2/graphene compositing methods is that some of them do not ensure the intimate contact between MoS2/graphene interfaces, an unfavorable condition for electrochemical applications (charge-transfer process).26 Finally, most of the present MoS2/graphene compositing methods are faced with the issue of low yield, ranging from several tens to hundreds milligrams of powders under laboratory conditions.To improve the electrical conductivity and enhance the structural integrity of MoS2/graphene composite. Our method is cost-effective, simple and scalable. The synthesis utilizes the thermal decomposition of solid precursor to generate MoS2; meanwhile, the released gas from the decomposition reaction blows premixed, melted glucose into crowded bubbles, which then evolve into graphene structures during annealing. The final product is microscopically featured as highly crystalline MoS2 nanoflakes distributed in three-dimensional (3D) macroporous monolithic graphene. With the additional assistance of intimate interfacial contacts between MoS2 and graphene, our composite demonstrates considerably improved electrochemical performance when compared with those of conventional MoS2/graphene composite upon application in NIBs. It is expected that such a unique MoS2/graphene composite should hold potential in promoting the development of practical MoS2 anode in NIBs, while the straightforward self-bubbling method could offer the opportunity in producing MoS2/graphene composites in industrial scale as well as synthesizing other advanced graphene-based composites.Herein, we report a single-step, template-free, high-throughput “self-bubbling” method for synthesizing MoS2 composite in this work. Empirically, thermal decomposition of (NH4)2MoS4 in inert atmosphere leads to MoS2 while releasing a considerable amount of gases.42,43 Results from our carefully conducted thermogravimetric and differential scanning calorimetry (TG/DSC) analysis for (NH4)2MoS4 decomposition in flowing Ar 2MoS4 (as MoS2 source) and glucose (as carbon source) with the setup of a two-stage annealing sequence to produce graphene/MoS2 hybrid, as shown in 4)2MoS4 remains solid inside it. Sequentially, during the second stage (from 200 to 1100 °C), (NH4)2MoS4 decomposes into MoS2 and crystallizes while the released gas species  blow the melted glucose to form crowded bubbles with ultrathin walls, which are then graphitized into 3D graphene networks at high temperature . With this simple approach, a rational nanostructure consists of MoS2 and graphene was obtained (hereafter abbreviated as MoS2@G hybrid). Besides, our approach also allows the MoS2/graphene ratio in the final product to be expediently tuned by using different ratios of (NH4)2MoS4 and glucose as precursors for various potential applications . The advantages of such novel approach include low cost, high flexibility, easy operability and excellent scalability. The complete annealing program is presented in Inspired by these findings, we started with a mixture of (NH2@G hybrid. The single production of the MoS2@G hybrid under our laboratory condition is up to ca. 1–2 g when a 1-inch (diameter) tube furnace was used, and the product is foam-like black solid 45,46 and provides a number of advantages such as excellent mechanical stability, high surface area, and effective avoidance of the graphene restack.The effectiveness of our approach could be fully confirmed by systematic microstructural analysis of the end-product. Firstly, microscopies were involved to reveal the morphological characteristics of the MoSinset of . An optiinset of  manifestinset of  suggest inset of  further 2 content. Transmission electron microscope (TEM) images in in situ experiment22), with a lateral size of 50–100 nm and thickness of 5–10 nm. As expected, the selected area electron diffraction (SAED) pattern in 2 structure (JCPDS no. 37-1492) while the bright diffraction rings reflect high crystallinity  planes) and interlayer distance of graphene (0.34 nm for (002) planes) as shown in the HRTEM images  can be identified throughout repeated observations. It should be noted that MoS2 structure with expanded interlayers is commonly considered to be highly beneficial to improve its electrochemical performance  for battery applications.20,27 In short, the above results consistently showed that the sample from our one-step self-bubbling approach was MoS2 nanoflakes distributed in macroporous few-layered graphene, in accordance with our original design. For comparison purpose, we also prepared pure MoS2 samples via the same process without glucose and the final product is mainly irregular microsized flakes .Our results also show that the graphene walls are decorated with nanosized particulates in the SEM images, most likely the result of the MoSM images , a favorM images , a sligh2@G hybrid. Concerning the chemical states of Mo and S in the product, 2 and MoS2@G hybrid, with their C 1s peak referenced at 284.8 eV. The presence of MoS2 with Mo and S elemental ratio of ∼1 : 2 can be identified for both samples, besides the prominent carbon component in the MoS2@G hybrid. The insets in 2@G hybrid, which are the S 2p, Mo 3d and C 1s regions. The Mo 3d possesses two peaks centered at 229.6 and 232.8 eV, in association with the doublet Mo 3d5/2 and Mo 3d3/2 for Mo4+ ions. Another group of peaks, ascribed to the S 2p3/2 and S 2p1/2 orbital of divalent sulfide ions (S2−), are observed at 162.4 and 163.7 eV, respectively. All these results are well consistent with the reported values for MoS2.25,47 The existence of Mo, S and C in the MoS2@G hybrid was also verified by the electron energy-loss spectrum (EELS), as shown in 2@G hybrid (inset in 2-bonded atoms) as well as a clear σ* step , suggesting the high crystalline nature of graphene in the hybrid.30,48Subsequently, spectroscopic characterizations were employed to further explore the microstructural features of the MoSinset in  presents2 and MoS2@G hybrid match with 2H molybdenite; however, the diffraction peaks of the MoS2@G hybrid are much boarder than those of pure MoS2, a result of the fine MoS2 crystalline size. Notably, the peak of (002) planes for the MoS2@G hybrid slightly shifts towards the direction of low scattering angle, corroborating the expanded interlayer distance as revealed by the above TEM results. The diffraction signal for graphene is not visible due to the intense peaks from MoS2 crystals, so Raman measurement was applied. As can be seen from the inset of 2@G hybrid exhibits two sharp bands at 1360  and 1600 cm−1 , as well as two broad bands at 2690 (2D band) and 2920 cm−1 (D + G band),49 which directly proved the existence of well-crystallized few-layered graphene structure in the hybrid. The hexagonal layered structure of the MoS2 in the hybrid was further confirmed by Raman spectrum with two peaks located at 383 and 407 cm−1 . As shown in 407 cm−1 , which a72.2 wt% .2@G hybrid was quantified by Brunauer–Emmett–Teller (BET) method. Results from the full nitrogen adsorption and desorption isotherms  method, are mainly distributed in the region of mesopores to macropores with a peak centered at 3.87 nm , the first peak at 1.20 V can be ascribed to the intercalation of sodium ions into MoS2 interlayer , the peaks from 1.4 to 1.7 V should be attributed to the oxidation of Mo to MoS2.27 In the subsequent cycles, the peaks at 0.66/0.56 V shift to 1.04/0.75 V with decreased intensity, corresponding to the progressive amorphization of MoS2@G hybrid. Notably, the CVs rapidly become overlapped in the later cycles, suggesting high reversibility for the electrode material. The stability of sodiation/desodiation processes was also confirmed by comparing the cycling performances of MoS2@G hybrid and MoS2 under the galvanostatic mode at a current density of 0.1 A g−1, as shown in 2@G hybrid delivered a capacity as high as 484 mA h g−1 at the 2nd cycle and 474 mA h g−1 at the 100th cycle . In contrast, the MoS2 electrode delivered only a capacity of 268 mA h g−1 at the 2nd cycle and 97 mA h g−1 at the 50th cycle. Furthermore, the CE of the MoS2@G hybrid (>99%) is constantly higher than that of MoS2.The above structural characterizations of our MoS2@G hybrid at 0.05 A g−1 in the potential window of 0.01–3 V vs. Na+/Na. The distinct discharge/charge plateaus in the first cycle are ascribed to the sample's high crystallinity.23 The discharge and charge capacities for the first cycle are 750 and 630 mA h g−1, respectively, corresponding to a CE of 83.7% , the electrode material can still retain ∼67% of its capacity (from 530 to 357 mA h g−1). Moreover, the MoS2@G hybrid is able to recover most of its original capacity when the current rate is restored back to 0.05 A g−1 after forty deep cycles, indicating the high stability of the MoS2@G anode even upon high rate cycling . It is worth noting that, during these repeated discharge/charge cycles, the volume change induced pulverization of the MoS2@G hybrid electrode has been significantly suppressed, as reflected by the constantly high CE (>99%) throughout the measurement and the comparative postmortem TEM study. As shown in 2@G hybrid indicates the existence of small MoS2 flakes firmly decorated on graphene sheets. The MoS2 content remains highly crystallized except the irregular outlines after such long cycling. Moreover, the uniform distribution of MoS2 on graphene sheets was also successful maintained. In contrast, the MoS2 sample shows considerable cracks across the flakes throughout the cycling . We believe that the unique microstructural features of the MoS2@G hybrid itself have brought multiple advantages to act as high-performance electrode materials. First, the thin MoS2 nanoflakes (5–10 nm in thickness) with expanded interlayer spacing (0.65 nm) greatly reduces the strain caused by insertion and extraction of Na+. Second, the high surface area of the MoS2@G hybrid (196.93 m2 g−1) provides a large electrode–electrolyte interface, in facilitating the critical charge-transfer process. Third, the monolithic graphene ensures a 3D porous and flexible scaffold to protect MoS2 from dissolution or detachment during repeated cycles, as well as 3D interconnected pathways for electron transport and Na-ion diffusion. Finally, the homogeneous distribution of MoS2 nanoflakes on graphene nanosheets together with their intimate contact guarantees good conductivity (for both Na+ and electrons), and hence a high level of electrochemical activity and effective material utilization of the MoS2 2MoS4 and glucose (weight ratio of 1 : 1.5) was directly subjected to thermal treatment in a horizontal furnace. As shown in The MoSα radiation . Raman measurement was taken using a Horiba Jobin Yvon LabRAM HR system with a laser wavelength of 488 nm. The nitrogen adsorption and desorption isotherms were obtained at 77 K with a Micromeritics ASAP 2020 volumetric adsorption analyzer.The samples were characterized by different analytical techniques. Simultaneous TG/DSC analysis was performed on a NETZSCH STA 449 C Jupiter system. Optical image was captured on a Nikon Microphot-FXA microscope. SEM observations were made on a JEOL JSM-6700F field-emission SEM. TEM images, SAED pattern, EELS, and EDS were obtained on a JEOL JEM-2100F STEM  system equipped with an Oxford INCA x-sight EDS and an ENFINA 1000 EELS. XPS spectra were acquired on a Thermo Scientific Escalab 250Xi spectrometer. XRD measurement was conducted using a Rigaku SmartLab Intelligent X-ray diffraction system with filtered Cu K4 in the mixed solvent of ethylene carbonate/dimethyl carbonate (1 : 1 v/v ratio) with 5 wt% fluoroethylene carbonate as additive was selected as the electrolyte for the coin cells. CV measurement was conducted on an electrochemical measurement system (PARSTAT 2273) with a scan rate of 0.2 mV s−1 from 3 to 0.01 V. Galvanostatic charge/discharge tests were performed by using a battery testing system (LAND CT2001A) within the potential of 0.01–3 V at room temperature. The capacities are given with respect to the total mass of the active materials throughout the work.The working electrode slurry was prepared by mixing the active materials with Super P and carboxymethyl cellulose binder at a mass ratio of 8 : 1 : 1. The slurry was then spread on the surface of a copper foil and dried at 60 °C for 12 h. Finally, the electrode was stamped into disks with a diameter of 10 mm and vacuum-dried at 60 °C for another 6 h. With sodium tablets as the reference electrode and glass fiber membrane as the separator, CR2032 coin cells were assembled in a glove box  filled with argon. 1 M NaClOL. F., C. L. M., and Y. W. conceived the idea and designed the experiment. L. F. and J. J. prepared samples. L. F., J. J., S. M. N., L.-L. S., L. S., and K. X. conducted structural characterizations. L. F. and M. X. performed electrochemical measurements. H. H. and C. W. L. contributed to critical discussions. L. F., C. L. M., and Y. W. wrote the manuscript, and all authors commented on it. Y. W. and C. L. M. supervised implementation of project. All authors have given approval to the final version of the manuscript. L. F. and M. X. contributed equally to this work.There are no conflicts to declare.RA-008-C7RA12617D-s001


Sarcoidosis has been and remains a challenge for patients and physicians alike. Even in the year 2022, the pathophysiology of sarcoidosis is still incompletely understood. With this Research Topic entitled “Sarcoidosis—The Great Mimicker,” we aimed to shed light on the various aspects of this enigmatic disease. We are thankful and indebted to all authors, reviewers, and external editors who have contributed with their research papers and time to make this a thriving collection of articles. We received many submissions indicating that sarcoidosis attracts researchers from various backgrounds and specialties. With this editorial, we will give an overview of the topics covered in the Research Topic and place them in the context of the current research landscape.Tirelli et al. describes a case of concurrent adenocarcinoma of the lung and coexistent sarcoidosis, which is rare and therapeutically challenging. A recent systematic review identified nine case reports and highlighted that meticulous diagnostic testing is essential to differentiate metastatic disease from sarcoid or sarcoid-like lesions (The search terms (Sarcoidosis[Title]) AND (Case Reports[Filter]) in the commonly used database Pubmed retrieved a steadily increasing number of cases over the years and a total number of 7.280 reports. Starting in 1955, only one case was reported, which increased to 276 as of 2021 . Thus, cDe Cinque et al. focuses on testicular sarcoidosis, an exceedingly rare manifestation of sarcoidosis. They reviewed the literature and identified, including their case, only 20 publications where testicular sarcoidosis was the primary manifestation of sarcoidosis. Most interestingly, they described contrast-enhanced ultrasound (CEUS) features, which can be helpful in discerning sarcoidosis from other malignant testicular lesions. Specifically, sarcoid lesions are hypoechoic and show hypo-enhancement on CEUS, a clinically relevant point.The following case report by Manansala et al. describe a case series of COVID-19 in sarcoidosis patients of African American ethnicity. They report on five cases; one ultimately expired due to a thromboembolic event. This report, published relatively early in the pandemic, was reassuring for patients with sarcoidosis, especially African American patients, who usually suffer more from sarcoidosis than other ethnicities -17 and−12/23-antagonists or B-cell modulating agents, were negative. Clinical trials for anti-IL-6, anti-IL-1, and Janus kinase inhibitors are ongoing and have not been published yet. In light of the recently published American Thoracic Society/European Respiratory Society recommendations for the treatment of sarcoidosis, which confirmed the lack of robust evidence derived from high-quality clinical trials, these trial results are eagerly awaited  and infrequent (neurosarcoidosis) manifestations. In addition, they highlight diseases and conditions that treating physicians always need to be aware of, such as drug-induced sarcoid reactions, common-variable immunodeficiency with granulomas, and differential diagnoses for hypercalcemic syndromes.Adding to the review papers on dedicated topics concerning sarcoidosis is the article by Chioma et al. described the role of the lung microbiome in interstitial lung diseases (ILD), including sarcoidosis. Among the few dedicated studies available, the evidence for alterations in the gut or lung microbiome is mixed. In sarcoidosis specifically, alterations of the microbiome in the lungs have not been firmly established.The last review of the topic by Cacciatore et al. analyzed a French cohort regarding acute vs. chronic sarcoid arthropathy. In short, chronic arthropathy tended to be less symmetric, had more wrist involvement, and more often required second- or third-line therapies.A total of four original papers were included in the topic. The first paper by Cameli et al. identified serum and urinary calcium levels as a useful biomarker in sarcoidosis. The investigators compared sarcoidosis patients with idiopathic pulmonary fibrosis and hypersensitivity pneumonitis. Further, receiver operating characteristics curve analysis revealed an excellent specificity (89.7%) of hypercalciuria for sarcoidosis vs. non-sarcoidosis ILD and a specificity of 82.5% for fibrotic sarcoidosis vs. non-sarcoidosis ILD. This paper highlights the importance of calcium and vitamin D dysregulation in sarcoidosis, which is an area deserving of further investigation.The subsequent exciting investigation by Nickles et al. analyzed similarities between discoid lupus erythematosus (DLE), cutaneous sarcoidosis (CS), and psoriasis by gene co-expression networks. These complex analyses revealed seven common hub genes in DLE and CS: TLR1, ITGAL, TNFRSF1B, CD86, SPI1, BTK, and IL10RA. Furthermore, these analyses also identified several disease-type specific hub genes. These results identified potential molecular targets for treating skin lesions of these diseases.The following paper by Vagts et al. used unsupervised clustering in a cohort of sarcoidosis patients who had undergone a positron emission tomography (PET) scan as part of their workup. A detailed analysis of clinical, laboratory, and imaging features revealed three clusters . In addition, the data showed a reduction in lymphocyte counts in cluster 3 and high PET avidity in clusters 2 and 3.Lastly, These results are relevant since the current recommendations for the diagnosis and detection of sarcoidosis  still veSarcoidosis remains an enigmatic and complicated disease. Within this Research Topic, experts in the field have shared their insights, experience, and research data to deepen our understanding of sarcoidosis. In our view, the agenda for future research includes but is not limited to: (1) what does assist us in making a confident diagnosis of sarcoidosis?, (2) the development of disease clustering criteria for clinical trials, (3) a definition of an applicable response index for measuring outcomes in clinical trials, (4) further explore the role of calcium/vitamin D metabolism in sarcoidosis, and (5) investigate the molecular mechanisms underlying the pathogenesis of the disease. Specialists from all fields, such as pulmonologists, rheumatologists, dermatologists, and neurologists, among many others, should embrace these challenges to improve the diagnosis and treatment of sarcoidosis patients for whom very few therapeutic options are available.PK conceived the article, wrote the manuscript, and created the figure. NS and MM reviewed and edited the paper. All authors contributed to the article and approved the submitted version.Author PK has received honoraria or travel support from Abbvie, Amgen, AstraZeneca, Boehringer Ingelheim, Bristol-Myers-Squibb, Chugai, Galapagos Biopharma, GlaxoSmithKline, Janssen-Cilag, Lilly, Pfizer, and Sanofi-Aventis, all unrelated to this paper. Author PK received research grants from GlaxoSmithKline and Diamed Medizintechnik GmbH, all unrelated to this paper. Author MM reports research awards from Mallinckrodt, advisory membership in Mallinckrodt. The remaining author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


The assembled MoS2/graphene catalysts exhibit significantly enhanced electrocatalytic activity and cycling stability towards the splitting of water in acidic solution. Furthermore, a strategic balance of abundant active sites at the edge of the S–Mo–S layers with efficient electron transfer in the MoS2/graphene hybrid catalyst plays a key role in controlling the electrochemical performance of the MoS2 nanosheets. Most importantly, the hybrid MoS2/graphene nanosheet paper shows excellent flexibility and high electrocatalytic performance under the various bending states. This work demonstrates an opportunity for the development of flexible electrocatalysts, which have potential applications in renewable energy conversion and energy storage systems.In this article, an exquisite flexible hybrid MoS 2/graphene free-standing electrocatalyst paper was fabricated by a one-step in situ solvothermal process for hydrogen evolution reaction applications.An improved flexible hybrid MoS One possible route to target is to utilize solar energy directly or indirectly  to split water to produce H2.1 Presently, producing H2 from the electrocatalytic splitting of water using the hydrogen evolution reaction (HER) holds tremendous promise because of the high energy efficiency and the economical and practical advantages.2 An advanced catalyst for the HER should play an important role in reducing the overpotential and consequently increasing the efficiency of this electrochemical process. Although the most effective HER electrocatalysts are Pt or Pt-based materials, their high cost and low abundance substantially restrict their large-scale application. Thus, it remains challenging to develop highly active HER catalysts based on non-noble-metal materials that are more abundant and lower cost.3–8To address the issues of the global energy crisis and environmental contamination, researchers have devoted considerable attention to hydrogen (H2) is a layered transition metal dichalcogenide (TMD), which has triggered broad attention as a typical two-dimensional (2D) semiconductor nanomaterial. The structure of MoS2 is based on a hexagonal crystal, where each Mo atom is six-fold coordinated, hexagonally packed between two three-fold coordinated sulfur atoms. Each S–Mo–S layer is weakly bonded to other S–Mo–S layers by van der Waals forces. Recent works showed MoS2 to be a promising electrocatalyst for the HER.9–15 It has been suggested that the electrocatalyst activation originates from the unsaturated sulfur atoms at the edges of the MoS2 plates, while the basal planes were often thought to be catalytically inert with some exceptions. As a result, nanosized MoS2 with a high degree of exposed edges should be more active for HER electrocatalysis than materials in bulk forms.16–18 Enormous effort has been dedicated to exposing more edge sites to enhance MoS2 HER activity by engineering various morphologies, such as nanoparticles,19 nanoplates,20 nanosheets,21,22 nanoflowers,23 nanoboxes,24,25 nanoporous films26 and heterolayer nanowires.27 The electrical conductivity of catalysts is another crucial factor affecting the electrocatalytic activity because high conductivity ensures fast electron transport during the catalytic process. However, poor electrical conductivity often exists both in dispersed nanostructure MoS2 catalysts and between the S–Mo–S layers of MoS2, restricting the activity.28 Considerable attention has been focused on accelerating electron transfer by coupling MoS2 with conductive substrates, such as nanoporous gold,29,30 3D Ni foam,31 metal oxides,32–34 activated carbon,35 carbon fibers,36,37 and carbon nanotubes (CNTs).38,39 Among these conductive supports, graphene, particularly reduced graphene oxide (RGO), has attracted much attention because of its excellent electron transport properties, chemical stability and solution-phase processing compatibility.40,41 Therefore, graphene supported MoS2 nanostructures appear to be highly active and stable electrocatalysts. However, all of the MoS2/graphene hybrid nanostructure catalysts mentioned above were prepared in powdered form. Thus they had to be dropped onto the surface of a conductive substrate (e.g. a glassy carbon electrode) and then be immobilized by binding Nafion or PTFE (polytetrafluoroethylene) polymer as a working electrode. As a result, the binding polymer might block some catalytically active sites, increase the series resistance, and thus decrease the overall activity of the material. For this reason, binder-free HER catalysts based on graphene with high electrocatalytic performance are highly interesting. On the other hand, an appropriate loading rate of MoS2 onto the graphene nanosheet is one of the significant parameters to study in MoS2/graphene hybrid electrocatalysts to balance abundant active sites at the edge of S–Mo–S layers with efficient electron transfer. However, so far there have been almost no reports on the activity of MoS2/graphene hybrid electrocatalysts sensitive to the MoS2 nanostructure loading rate.Molybdenum disulfide  was added, and the mixture was stirred for 10 min in an ice water bath. Then, 0.5 g of NaNO3 powder was added and stirring continued for 20 min. Next, 3 g of KMnO4 was slowly added to the flask, keeping the reaction temperature below 5 °C for 30 min. Then, the solution was heated in an oil bath at 35 °C and allowed to stir for 0.5 h. Afterward, the flask was removed from the oil bath, and 50 mL of water and 5 mL of 30% H2O2 were added to end the reaction. The obtained dispersion was filtered and washed with 10% HCl aqueous solution followed by ample water to remove metal ions and residual acid, respectively. The resultant GO solution was sonicated for 1 h and centrifuged at 5000 rpm. The concentration of GO was determined by weighing the quantity of GO by vacuum freeze-drying 10 mL of GO solution. The final concentration of GO solution was modulated to 5 mg mL−1.GO was made using a modified Hummers’ method. Briefly, 1 g of graphite powder was put into a 250 mL round-bottom flask. A total of 25 mL of concentrated H2/GO nanosheets were synthesized through a one-step solvothermal reaction according to Dai’s group’s method.42 Briefly, 25 mg of GO was dispersed in 40 mL of dimethylformamide (DMF) solution and stirred for 10 min. Then, different amounts of (NH4)2MoS4  were added to the mixture, followed by sonicating for 10 min to obtain a well dispersed solution. After that, the solution was transferred into a 50 mL Teflon-lined stainless steel autoclave and sealed for reaction at 210 °C for 12 h. After cooling down, the black products were collected by centrifugation at 8000 rpm for 3 min and washed repeatedly with DI water and ethanol 3 times. Finally, the hybrid suspension was vacuum filtered using polyvinylidene difluoride (PVDF) membranes . The wet MoS2/GO composite paper along with the PVDF membrane was fabricated, then washed with ethanol to remove the remaining solvent. After vacuum freeze-drying, the composite paper could be easily peeled of as a freestanding MoS2/GO paper. The hybrid papers with various loading amounts of MoS2 were denoted by weight percentage content as: MoS2/GO-5%, MoS2/GO-10%, MoS2/GO-20%, MoS2/GO-30% and MoS2/GO-40%. To obtain highly conductive graphene sheets and highly crystalline MoS2, the MoS2/GO composite papers were cut into 2 cm × 1 cm pieces, then heat-treated at 700 °C for 2 hours in Ar flow with a heating rate of 6 °C min−1. For comparison, pure RGO paper was also prepared via the above method without the addition of the (NH4)2MoS4 precursor.MoSθ = 10° to 80° using a Bruker Advanced D8 diffractometer under Cu Kα radiation (λ = 0.1542 nm), with a voltage of 40 kV and a current of 40 mA. The phase structures were characterized using Raman spectroscopy (Jobin-Yvon HR800), with the excitation source an argon-ion laser (λ = 515 nm). Transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM) images were obtained under an acceleration voltage of 200 kV with a FEI Tecnai G20 TEM instrument. The high resolution energy dispersive X-ray spectroscopy (EDS) mapping measurements were carried out with a probe-Cs-corrected HRTEM instrument (FEI Titan G2 60-300) in scanning TEM mode (STEM). The chemical composition and bonding states were investigated by X-ray photoelectron spectroscopy  using an Al Kα source 1486.6 eV anode. All XPS spectra were corrected using the C 1s line at 284.6 eV.The morphology of the as-obtained products was observed using field emission scanning microscopy . X-ray diffraction (XRD) was carried out from 22SO4 at room temperature using an electrochemical workstation . The prepared MoS2/graphene freestanding paper was measured as a working electrode. A commercial 20% Pt–C catalyst was used as a reference sample. An Ag/AgCl electrode with saturated KCl solution and a Pt wire were used as the reference electrode and counter electrode, respectively. The potential values reported in this study are versus the reversible hydrogen electrode (RHE). The HER activities of the samples were evaluated using linear sweep voltammetry at 10 mV s−1. Continuous cyclic voltammetry (CV) was conducted at 50 mV s−1 between 0.1 and −0.5 V to investigate the cycling stability. EIS was carried out from 105 to 0.1 Hz with an amplitude of 10 mV at the open-circuit voltage.All electrochemical experiments were performed in a standard three electrode setup in 0.5 M H2/graphene nanocomposites and prepare the free-standing MoS2/graphene electrode paper using a vacuum filtration method, which was a facile and time-saving method. 2/graphene freestanding paper after peeling off the membrane, with a size of 2 inches. The hybrid film appeared uniform and was a dark gray color. These freestanding papers can be randomly wrapped around a glass rod with no noticeable damage, indicating their remarkably flexible and durable properties . The hybrid MoS2/RGO films show two diffraction peaks relating to RGO and MoS2 (100), respectively. The absence of a (002) low-angle diffraction peak indicates that the atomic arrangement of MoS2 in the hybrid with graphene sheets was different from that in the powder form. Raman spectroscopy, as shown in 2 at 378 and 402 cm−1, corresponding to the E2g1 and A1g modes as shown in the inset, respectively. The lower intensity of E2g1 (in-plane Mo–S phonon mode) compared to that of A1g (out-of plane Mo–S phonon mode) indicates that the MoS2 crystals tended to show the basal-edge-rich feature of the ultrathin plate growth, in good agreement with the absence of a (002) peak in the XRD measurements.We employed a one step solvothermal reaction method to synthesize the MoSinset in . Fig. 1b2/graphene nanosheets were further obtained by TEM. As shown in 2 nanosheets are homogeneously dispersed on the graphene sheets, indicating that the graphene sheets could be used as an efficient substrate for the nucleation and growth of MoS2 nanosheets. On the other hand, the graphene sheets show good ability to prevent the aggregation of MoS2 nanosheets, serving to enlarge the active area of HER. Furthermore, plate-like ultrathin MoS2 can be further verified by HRTEM, where each sheet contains several S–Mo–S layers with an interlayer spacing of 0.62 nm, as shown in 2 nanosheet, in agreement with the results of XRD and Raman characterization. Furthermore, two different aligned  MoS2 nanosheets were found on the GO sheet under higher resolution TEM investigations, as shown in 2 show that a few layers of MoS2 were stacked with hexagonal lattice symmetry. Part of the MoS2 layer is fully vertically aligned, resulting in dominantly exposed molybdenum or sulfur atoms, which is beneficial for higher chemical catalytic activity for the MoS2 sheets. The HRTEM image indicates the vertically aligned MoS2 composed of a several-layer structure and a lattice fringe spacing of 0.62 nm. The chemical composition of the hybrid nanosheet was further determined by an energy dispersive X-ray spectroscopy (EDS) curve and mapping using a probe-Cs-corrected TEM instrument. 2/GO hybrid films. The results show that there were six kinds of element  detected, of which C and O peaks come from GO, Mo and S come from MoS2, and Cu and Si come from the TEM grid and silicon escape peak. 2/graphene nanosheet hybrid structure. The signal for O comes from the incomplete reduction of graphene oxide after the solvothermal reaction. To obtain highly conductive graphene sheets, the freestanding MoS2/graphene paper was further treated by annealing at 700 °C for 2 h in Ar flow.The morphology, microstructure and chemical element information for the ultra thin plate MoS2/graphene catalyst films were carried out to elucidate the chemical bonding structures. A typical XPS survey scanning in the binding energy range from 0 to 1200 eV is shown in 2/graphene hybrid film, Mo, S, O and C elements were detected. Meanwhile, the S 2p region  and intact (ACC) carbon atoms, as shown in 2 carbon  scale" fill="currentColor" stroke="none"><path d="M0 440 l0 -40 320 0 320 0 0 40 0 40 -320 0 -320 0 0 -40z M0 280 l0 -40 320 0 320 0 0 40 0 40 -320 0 -320 0 0 -40z"/></g></svg>C, 284.3 eV) and epoxy/hydroxyls , respectively. The ratio ACO/ACC of annealed MoS2/graphene is about 0.25, which is much lower than that of the GO nanosheet published elsewhere,43 indicating that the GO sheet has been reduced to RGO efficiently by annealing.X-ray photoelectron spectroscopy (XPS) analyses of the annealed MoSp region  exhibits2 play a key role in improving the HER activity.29,44 Therefore, efficient HER activity can be expected for the higher loading rate of MoS2 in the hybrid films, which introduced more edge sites. We investigated the HER activities of our MoS2/graphene hybrid thin films with different loading rates. The electrocatalytic HER performance of freestanding MoS2/graphene paper was measured in 0.5 M H2SO4 solution using linear sweep voltammetry (LSV) in a three-electrode system. The polarization curve was recorded within a cathodic potential window in the range 0.1 to −0.5 V at a 10 mV s−1 scan rate. For comparison, pure RGO film and commercial Pt–C were also assessed. 2/graphene hybrid films loaded with various MoS2 nanosheet percentages from 5 to 40%. All the polarization curves have no IR compensation. As expected, the commercial Pt–C catalyst displayed the highest electrocatalytic activity, with an onset overpotential  of 23.9 mV. In sharp contrast, the pure RGO film without MoS2 nanosheets exhibited the lowest electrocatalytic activity. The onset overpotential gradually decreased from 263.7 mV to 94.2 mV when the MoS2 nanosheet content percentage increased from 5% to 30%. However, in contrast the overpotential increased to 221.6 mV when the MoS2 nanosheet percentage was 40%. Generally, the overpotential value for a HER current density of 10 mA cm−2 is an important reference because significant hydrogen evolution can be observed and the solar-light-coupled HER apparatuses usually operate at 10–20 mA cm−2 under standard conditions .45 According to a previous report, monolayer MoS2 loaded on a 3D nanoporous gold substrate shows a low operating voltage of 226 mV as a typical overpotential for a few-layer MoS2 nanosheet.29 To achieve this current density in this work, the 5 wt%-MoS2/GO catalyst requires an overpotential of 490.2 mV. Moreover, the overpotential shows an obvious decrease from 430.3 mV to 238.5 mV when the weight percentage content of MoS2 nanosheets increases from 10% to 30%, which indicates that the MoS2 nanosheets have significantly accelerated the HER process. However, the overpotential was remarkably increased from the lowest value 238.5 mV to 377.2 mV, as the MoS2 loading rate increases from 30% to 40% in the MoS2/GO hybrid thin films, which indicated that the HER activity was suppressed in the catalyst in spite of the higher loading rate bringing more active sites. We speculate that the surface loading rate of the RGO film was the major reason for the HER activity performance degradation. Part of the MoS2 nanosheets were interstitial in the RGO hybrid thin films when the concentration of the MoS2 precursor was higher than the loading capacity of the GO sheets. This may lead to inefficient electron transfer because of the semiconducting properties of the S–Mo–S layers. For comparison, I–V curve measurements of the thin hybrid film with various loading rates were carried out to elucidate their electrical resistivity  after 50 hours of durability determination, indicating that MoS2/graphene nanosheet catalysts are stable electrocatalysts in acidic solution.The stability of the MoS46 Therefore, it is highly interesting and urgent to investigate flexible electrocatalysts to develop a flexible power source with remarkable electrochemical performance for integration into flexible electronics.47 To develop flexible electrocatalysts, the catalytic performance should remain unchanged under various bending states. The current stability of MoS2/RGO hybrid films under four various bending curvatures was monitored at a fixed voltage of 1 V (2/RGO catalyst was hardly affected by bending stress. Furthermore, the effect of the flexibility of MoS2/RGO on catalytic activity was investigated at four various bending states, as shown in 2SO4 acidic solution at 10 mV s−1. It is clear to see from 2/RGO is an excellent flexible electrocatalyst and its electrocatalytic activity is almost unaffected by the various bending states.Recently, flexible and wearable electronic devices and energy storage and conversion systems, such as flexible displays, supercapacitors and solar cells, have attracted great attention.e of 1 V , and eacin situ solvothermal process for the fabrication of improved flexible hybrid MoS2/graphene free-standing electrocatalyst paper for HER applications. The MoS2/graphene catalysts exhibit significantly enhanced electrocatalytic activity and cycling stability towards the splitting of water in acidic solution, indicating the promising potential of solar energy. Furthermore, a strategic balance of abundant active edge sites with efficient electron transfer in the MoS2/graphene hybrid catalyst plays a key role in controlling the electrochemical performance of the MoS2 nanosheets. Most importantly, because of invariant performance under various bending states, the MoS2/graphene hybrid films provide a fundamental opportunity for the development of flexible electrocatalysts, which have potential technological applications in renewable energy conversion and energy storage systems.In conclusion, we have demonstrated a one-step There are no conflicts to declare.RA-008-C8RA01226A-s001


Brands can be defined as psychological constructs residing in our minds. By analyzing brand associations, we can study the mental constructs around them. In this paper, we study brands as parts of an associative network based on a word association database. We explore the communities–closely-knit groups in the mind–around brand names in this structure using two community detection algorithms in the Hungarian word association database ConnectYourMind. We identify brand names inside the communities of a word association network and explain why these brand names are part of the community. Several detected communities contain brand names from the same product category, and the words in these categories were connected either to brands in the category or to words describing the product category. Based on our findings, we describe the mental position of brand names. We show that brand knowledge, product knowledge and real word knowledge interact with each other. We also show how the meaning of a product category arises and how this meaning is related to brand meaning. Our results suggest that words sharing the same community with brand names can be used in brand communication and brand positioning. Brands can be seen as companies’ most valuable assets. The literature describes brands in different contexts, e.g. distinguishing symbols or entities influencing consumer decisions –4. A recOne possible research direction interprets brands as entities of the mind (cf. e.g. Franzen and Bouwman in ). BrandsBrands occupy a specific position in the mind. This mental position can be determined by the words (and concepts) associated with brands , 7. ThesBoth Aaker  and KellAs Dzyabura and Peres  point ouAs we see, brand meaning can be defined through the associations connected to a brand. For this reason, the associations that brand names evoke in our minds are important brand assets. But equally important are the words which evoke the brands–the cues from which a brand name comes to our minds . Since tWord association databases provide an opportunity for analyzing cues that evoke brand names. The data in these databases are word association data, where a cue word is presented, and respondents have to name the first word that comes to their mind when seeing the cue word. Brand names regularly occur in these databases, and they enable us to gain an insight into the mental representations and connections of brand names.In our paper, we analyze one such database with methods from network science. We examine the connections around brands; we search for communities–closely-knit word groups–of the database with two different detection algorithms.In the first part of the paper, we describe associations. We then show why association databases can be seen as networks and how networks and communities can help us to better understand the structures of word association data. Finally, we show that brands in the mind can be analyzed as parts of the mental network.In the second part of the paper, we analyze the brand-related communities of a Hungarian word association database and show communities in which brand names appear. For finding communities, we use the hub percolation method , 18, theBased on the results and previous research, we define how brand names are stored in the mind’s communities, and we show that these word communities share brand and product characteristics.Words–or more precisely, lexical units–in the mind carry pieces of information; information about a word’s frequency, meaning, morphology, phonology and syntax is stored together with pragmatic, stylistic, graphemic and encyclopedic knowledge , 22.Words stored in the mind can be researched by collecting and analyzing word association data. In word association experiments, a cue word is presented to the participants, and they must write down or name the first word that comes to their minds. The method has been known since Galton , 24 and Word associations can be collected in several ways; participants can name a single association or multiple associations. Associations can be restricted where some characteristics of the allowed answers are determined (e.g. the word class of the response). In some experimental settings, participants are asked to name all of the associations that come to mind (i.e. continuous associations). The used methods, their variants and early results of word association research are described by Cramer .Word association data is never the data of one individual; data is collected from hundreds or thousands of participants. Thus, the database represents not just the connections of one individual; rather, it represents an aggregate of all the connections we can build between words. Word association research has created several word association databases –30.Since the 2000s, the method has experienced a renaissance; new, large-scale data is available, and methods from other disciplines–above all network science–can be used to analyze and describe the characteristics of the connections in the mind –33. One All in all, word association networks can be used for the description of several cognitive tasks, for example, predicting lexical norms , memory The concept of graphs (or networks) has been studied extensively, first as a branch of discrete mathematics. The usefulness and expressivity of the concept became increasingly apparent as other fields started adopting it into their methodology, including sociology, biology, economics and linguistics . NetworkNetworks also provide a natural way to describe word associations; words are connected when one word–the cue–primes another , 32. TheNetworks in real life share several common characteristics. One of these is community structure; a network’s nodes can be grouped into sets so that the nodes inside the sets are densely connected, while the links between the sets are relatively sparse , 49.In social networks, this phenomenon corresponds to the tendency of people to form groups according to common interests and occupations. Word association networks also have a distinct community structure. It has been shown that the communities have an overlapping character in word association networks , and worCommunity detection, the identification of communities in a network, is a very popular subfield of network science, and a great many algorithms have been proposed to solve this task. The majority of the literature defines communities in undirected, unweighted networks and does not allow overlaps between the identified groups. The most notable approaches include modularity maximization methods , 42, stoThe idea of mental networks has a long history in psychology and linguistics , 63. In Similarly, it has been assumed since the 1990s that brand names are also part of these networks; they are represented by nodes in memory and connected via different types of connections to each other, brand and product characteristics and other words . Brands Early research only formulated assumptions on how the network structures around brands are organized–empirical data was missing . ResearcThere are several possible methods to analyze and create these brand-related networks. One of the earliest empirical analyses of networked structures around brands is from Henderson, Iacobucci and Bobby , 70, whoThe most often used method is creating Brand Association Maps , 69, 71,Assuming that brand names are stored like lexical units, phonological and graphemic information and meaning are also stored with brand names. However, the meaning of a brand name arises differently than a word’s meaning. A brand itself can be seen as ‘a cluster of meanings’ [10: 6], where a brand is ‘the consumer perception and interpretation of a cluster of associated attributes, benefits and values’ [10: 6].Based on existing research , 74, we product categorycountry-of-originlogocolorssloganexperiences with the brandexperiences of others with the brand  Are brand names parts of communities in the mental lexicon?RQ2) Are overlapping or non-overlapping methods better for brand community detection?RQ3) What is the advantage of analyzing communities around brands instead of associations connected to brands?Based on the results, we describe how brand names are represented in the mind and show the implications of the results.Research data used in this paper was collected from the word association database ConnectYourMind, which collected associations online between 2008 and 2014, primarily in Hungarian. During that period, approximately 182.000 associations were collected from 1035 respondents.The data collection was a classic word association experiment online. Participants were shown cue words, and as a response, they had to write down any words or combination of words that came to their mind. In the experiment, no restrictions were given according to the responses; any word or part of a sentence (up to 255 characters) could function as a response to the cue words. Responses could be proper names or inflected forms. The language of the responses was also not restricted; thus, the website also collected data–although only several hundred words–in English, German and Italian.The data was collected in two ways; the first 134 words appeared in a given order to all respondents. These 134 words were the initial cue words of the database . After tParticipants took part in the experiment voluntarily, and they could end the experiment anytime by simply navigating away from the webpage. Details of the data collection are described in more detail in  and exhaWhile the mean number of responses per user was 156, the standard deviation of this value was 155, showing that there was a considerable difference in user patience. This also means that the first cue words received more associations than the rest, and we acknowledge this as a limitation of our work.The database contains 699 brands annotated by an expert. The distribution of brands inside the word associations is highly inhomogeneous, with the top 50 brands receiving 50% of the total number of associations containing brands .. As we The network itself is constructed in the following way: the connections between words represent the cue word–association relationship. In the network, each word represents a node, and each given association (response) is represented as a directed, weighted edge in the form of a cue word → response. For example, to the cue word “apple”, a respondent typed in “pear”; in the database, the word “pear” was stored, and a connection between them was created: apple → pear, with a connection strength of 1. When a second person gave the same answer (again pear to apple), the strength of the connection was increased . In the database–due to the data collection process–the first 134 words collected more associations and enabled a deeper analysis of the associative structure for these words . On the We used community detection to create the groups of associations examined in this paper. We applied several detection algorithms to determine which one fits our specific application best. We have experimented with the following non-overlapping, overlapping and directed algorithms:The hub percolation method  is a cliDirected hub-percolation , the dirThe modularity maximization method of  is basedThe Infomap algorithm  seeks toStochastic blockmodels  are geneThe LEMON algorithm is an overlapping detection algorithm based on local expansion via minimum one norm . The metWe applied all of the above detection algorithms to the Hungarian word association network and measured their performance according to multiple metrics, such as conductance , hub-domWe can see that different methods capture completely different aspects of the community structure of the word association network. Modularity maximization produces low-transitivity communities organized around hubs, with relatively low modularity for the end result. As can be expected from a clique-based method, hub-percolation identifies many small, quasi-clique communities with high transitivity and hub-dominance. The directed version of the algorithm produces the opposite: few large communities. SBM inference could not find a sufficient number of communities. The LEMON algorithm had the advantage that community seed candidates could be provided as inputs of the algorithm. We used expert-annotated brand names for this purpose.However, since our aim in this paper is to examine the association network’s communities from the perspective of brand analysis, we ultimately selected the methods that promised to provide the most meaningful results from this practical perspective. These were undirected hub-percolation, the LEMON algorithm and modularity maximization. The LEMON algorithm was especially useful in our analysis, since we are interested in communities organized around a priori known brand names and we could simply provide a list of brand names to the algorithm as input, which would then grow communities around them. Both the star-like structure of the communities identified by the modularity maximization algorithm, and the high-resolution quasi-clique communities found by undirected hub-percolation were easy to interpret.In the first step of our analysis, we searched for communities in our word association network with the two community-finding methods defined in the previous section. In the identified communities, we searched for brand names manually. We define brand names as any name that can influence consumer decisions. We do not differentiate if the brand name is a registered trademark or not, an umbrella brand name or an individual brand name, or a product or a services brand.The first detection algorithm we used was the hub percolation method , 18. TheAltogether 81 communities contain brand names. Large communities– 70+ words–are heterogeneous , and if more brand names appear in one community, they are partially from different product categories.CIB, OTP, MKB, CIB Bank and Erste appear–all brand names of banks operating in Hungary. The same applies to community nr. 183 (54 words), containing the brands Alcatel, T-mobile, v630i, Nokia, Sony, Blackberry, Motorola, LG and Samsung–mobile phone brands and a service provider from the pre-smartphone era in Hungary (note: data collection took place between 2008 and 2014). Likewise, community nr. 642 (30 words) contains Nokia, iPhone, Apple, Motorola, Samsung, HTC and Sony. It is also interesting that if a community has one brand, it likely has another. However, some communities contain brands from different product categories; community nr. 116 (65 words) contains Gucci, Mercedes, Bugatti and Audi, of which three are car brands and one is a fashion brand. However, all can be considered brands in the luxury segment of the given product category; thus, they share the same segment, although in different product categories.The picture changes when the communities become less than 70 words. In this case, the communities containing a brand name tend to contain more brand names, and these brand names are clearly related to each other. Like in community nr. 111, containing 66 words, the brand names The pictures change again in communities with less than 20 members; communities containing brand names only have a single brand name. The picture from the used community detection method is not clear. Communities having between 20 and 70 members seem to be homogeneous considering brand names. Under a homogenous community, we will understand a community where the brand names are from the same, or closely related, product categories; for example, when only vehicle brand names appear in a community, we consider it as homogenous regarding brand names. Communities above this size are heterogeneous, and below this size, they contain only one brand name as a member.Citroën, Xsara, Honda, Accord, Yamaha, Toyota, Suzuki, Avensis, Peugeot, Mx-5, Subaru, Volkswagen, Alfa Romeo, Fiat, R5, GTO, Polo, Micra, Nissan, Suzuki Hayabusa), community nr. 23 has lifestyle brands, mostly watch brands  and community nr. 280 has 40 members with the brands Gucci, Dior, Armani and Prada.Using another overlapping algorithm (LEMON), all communities are guaranteed to have brand names. The communities found by the algorithm are–according to brand names–homogenous. The brand names in a given community belong to the same product category or closely related product categories; for example, communities nr. 4 and 6 consist of vehicle brands  and prestige (presztízs), and with the expression expensive things (drága dolgok). It is clear that this community is centered around (expensive) brands; hence, brands of different product categories are present.However, heterogeneous communities–brands from different product categories–were also identified, for example, community nr. 62., 81 words, 29 brands: Citroën is part of 24 communities, Ferrari of 18 communities, and Nikon of 31 communities. This means that based on this database, to have a clear picture of the brand Citroën, all words in 24 different communities should be researched, and the connections between the words should be analyzed.It is clearly impossible to verify one-by-one the consistency and all words of all communities; it can be said, however, that from brands’ point of view, most communities seem to be homogenous. The algorithm produces good, overlapping results; thus, due to the overlapping nature of the method, it is possible to see several community structures the brand is part of–on the other hand, the analysis is impeded exactly by the fact that several contexts have to be analyzed and minor differences must be accounted for. For example, the brand name To refine our results, we decided to use the modularity maximization algorithm of Blondel et al.  to see iOf the 692 communities, 32 contained brand names. With this method, the brand names in the communities were from the same category or product group. The communities detected with these methods were more homogeneous than the ones detected by the hub percolation, making it possible to determine the key words and ideas the community is structured around. The key words of the community were identified manually by the authors. We used the automatic detection method–manual analysis in line with Brookes and McEnery .Rolex and Swatch appear; and in the community ‘fashion’ (83 words), we found the fashion brands Gucci, Armani, DG, and Mayo Chix along with A´rka´d (a shopping center), Takko (a textile discount store) and L’Or´eal. In this community, we found the city names Paris and Milan too. In the community ‘reading and news’, brand names of newspapers, magazines and television channels appear (31 from 145), and names of writers  and fictional characters (Bridget Jones) are also present.For example, in the community ‘credit and banking’, the appearing brand names are all banks (11 brand names from 84 words); in the community ‘shopping’, they are supermarkets, discount supermarkets and local chains (15 from 148 words); in the community ‘time’ (54 words), two watch brands, Ferrari, Greenpace, Fradi (a Hungarian soccer team with distinctive green color), Jonathan (an apple name), Snow White and the Smurfs, with their Hungarian name Hupik´ek T¨orpik´ek (‘blue smurfs’). The last two are brand names usable for merchandising and licensing . It contained the name cf. Lind , Simon ).Running the LEMON algorithm, however, we found that 18 communities contain the brand name Ferrari (and 28 communities contain Volkswagen). It is clear that 18 (or 28) meanings of a brand do not exist. For Ferrari, we could name as broad categories 1) the brand context , 2) the product context–and/or 2a) sportscar and/or 2b) luxury car, 3) another product context for luxury products and, perhaps, 4) a lifestyle context together with brand use. Seeing the communities of LEMON, however, we found that these possible contexts are simultaneously present in each community.The overlapping community detection method provided good results as it managed to identify communities and brands in the communities, and the communities themselves are explainable in the product-brand context. However, the method failed to distinguish between brand and product meaning.We are aware that current results would suggest that better–marketing-relevant–results can be obtained by using only non-overlapping methods for community detection. It must be stressed, however, that the structure of the mental lexicon is overlapping by its nature; therefore, community detection methods must be improved to provide results that can also be used for practical purposes (e.g. showing the exact contexts brands are part of in our minds).Our results show that we must distinguish between brand associations and associations around brands (RQ3).Brand associations are the associations brands trigger. However, as we have seen in the case of communities, associations do not have to be connected to a brand name to be in the same community as the brand name (cf. point 3). This result aligns with secondary and tertiary associations described by Keller . SecondaThe question arises: Why are community detection methods better as simple associations to explain the mental position of brands (RQ3)?To answer this question, we must first consider the above description of secondary and tertiary associations; these are the associations that are not directly connected to the brand. How can we trigger these associations? Clearly, naming the brand as a cue word is not enough as it collects only the brand’s direct associations. We can also come up with some ideas about which words would trigger the brand name itself , but it is unlikely we will test all possible triggers. Here word association data could come into play; they are collected not focused on a given brand but focused on the research of the mental lexicon. Therefore–as we have seen–brand names will be part of these databases, but they are not the focus. As an example, we take two Hungarian mineral water brands, Theodora and Szentkirályi , and FerAs we can see, the direct network is not complex, while the community structures present a more complex structure with secondary and tertiary associations, showing not only the structure in the immediate vicinity of the brand.Brand association data is collected by presenting the brand name as a stimulus, thus picking out an entity (a brand) from the complex networked structure of the mind and analyzing the picked out entity alone, without knowing the surroundings it naturally has in the consumer’s mind. This shortage of brand analysis is known to research; hence, the recommendation to also study secondary and tertiary associations :brand names (Audi)brand/product characteristics brand/product parts and ingredients (wheel)contexts where the brand/product is used results of using the brand/product substitute product (bicycle)The observed words in the identified communities are in line with brand associations in general , 6, 7. OAlthough the starting point of our research was not brand names–we did not initially use brand names as cue words–we identified associations that are in line with brand-focused research. These results show that when describing a brand’s cognitive position, it is advisable to take into account not only the associations a brand is directly connected to but also the complex associative structure around brands.In this regard, the communities contain brand information and product information (see previous point and literature review). We surmise that the associations of brands define the meaning of the brand, while communities around several brands define the meaning of a product category. Thus, communities do not necessarily provide relevantly more information about a brand compared to other marketing research methods; rather, word association data and communities can help to gain a deep insight into product category information and the interacting connection between product categories and brands. The method has the advantage of using one large dataset to answer several product- and brand-related research questions with the same dataset and directly compare the differences and similarities of different brands (thank you for a reviewer to pointing out this advantage).In addition, the gained information may help to plan advertisement campaigns more precisely; words from the community (which are not directly connected to the brand) may help to formulate messages, which are more easily accepted by the target group since the words are already part of the community. However, at the same time, words missing from the communities can also show what words may be used for differentiation from other brands (see Implications).At this point, it is important to emphasize an assumption that arises from previous research but has to be verified empirically in the future.As described in 2.1, lexical units store several different pieces of information in the mind, and the stored information enables an effective organization of the units and helps to connect them , 107. ExSince brand names were present in word association experiments, we assume that brand names are represented as nodes in the mind, connected to other words and brand names  and some language-specific information . Pieces of this multisensory information are always present and active, regardless of the language and linguistic context. For example, driving in a foreign country and seeing the logo of a fast-food brand, all the information about the brand, products, price category and tastes will be activated, even if one does not speak the language of the given country.This assumption–if verified–could indicate that for a global brand, it is important to use brand communication patterns, which are not country- and language-specific, meaning that, for example, texts should not be the focus of an advertisement. The focus should be multisensory, language-independent information, which in the consumer’s mind does not need to be connected to a given language, thus enhancing the storage of brand-related information on the encyclopedic layer. This may result in brands relying on techniques that are accessed more easily in a context where text is less relevant (e.g. in a foreign country).Several well-known global brands seem to use this technique already. It should be interesting to learn whether the global success of these brands was connected to the fact that they–unconsciously to the layers of the lexicon–used the method described above in their campaigns.We must note that, at this point, this is only an assumption based on the analysis of one database.The description of brand names as nodes belonging to closely-knit communities in the mind shows that brand communication of a well-known or young brand cannot exist in an empty space–all the other brands and the product category the brand belongs to and the attitudes and expectations of consumers towards the product category shape how the brand is perceived.Product-related communities–and words in these communities–may be used by new brands in a product category. First, new brands (and brand names) have to be connected to the product category in as many ways as possible to ensure that the new brand is immediately perceived as part of the given product category and thereby benefits from all the associations of the product category. This can be done by using words in advertisements, which are part of the community of the product category.At the same time, however, they have to ensure that the community around the brand is different from the communities of all other brands and that it contains not only product-related characteristics but also a distinctive logo and slogan that are specific to the brand. A good example is the Hungarian herbal liqueur Zwack Unicum. It is a widely known Hungarian brand with over 100 years of history. It has a distinctive product feature: its bottle has a unique round shape that characterizes the brand. A previous experiment showed that the shape of the bottle frequently appears as a brand association with words like bottle shape, small round bottle, small spherical bottle, round bottle, round, shaped bottle, round, sphere .Advertisements could profit from a better understanding of communities around brands . An examAs we can see in the community in Why is this important? As seen, the community of the product category mineral water already contains the word healthy. Using this word in an advertisement will not help to differentiate a brand–it emphasizes, however, one important feature of the product. Since the word healthy is already part of the community centered around mineral waters, this strong connection can be used in advertising (cf. Shamsollahi ). On theThe communities around brand names are not necessarily the same as those communicated through advertisements and marketing efforts. The meaning of a brand and its perceived and accepted characteristics always develop through a negotiation process between the brand owner and society. The result of this process is the actual meaning of the brand in a given society, which can be different from the meanings the brand owner intended to engrave into the brand , 110.The communities around brands and product categories can contribute to finding these negotiated meanings of brands. Neglecting these meanings can result in brand disasters. In this regard, the communities identified by our analysis can be used to see whether the brand is positioned in the mind of the consumer the way the brand owner intended. Therefore, it is important to analyze not only associations connected to a brand but also the complex associative structures and communities around the brand and the whole product category.Current results are obtained from a word association database collected for linguistic research. Although some demographic variables were collected, no information was asked from the respondents about their brand or product preferences. Therefore, whether the found community structures are general or user-group specific cannot be analyzed.It must be assumed, however, according to Franzen and Bouwman  (cf. 1111), thatIn this paper, we analyzed communities in a word association database and searched for brand names inside the communities.We started with hub percolation, and results showed that the communities we detected identified communities around brands, with the communities being partly homogenous. The LEMON algorithm provided good results since it takes initially known members of communities as an input. We are interested in communities organized around previously known brand names, and we could simply provide a list of brand names to the algorithm as input, which would then grow communities around them. The communities provided by the modularity maximization algorithm were homogeneous and focused on individual brand names from the same product category, enabling us to better explore the associative structures around product categories.Our results showed that brand names are present in word association databases, and we found that the algorithms were able to find homogeneous communities in these databases. We also showed that communities contain brand names from the same product category since brands of a given product category share common characteristics.Based on the results presented here and our previous works, we described how brand names are stored in the mind; they are multisensory entities strongly connected to the product category. We also showed that overlapping and non-overlapping algorithms both provide valuable insights, but currently, non-overlapping methods provide results that are easier to interpret. We also showed that communities in the mind play several roles; communities around brands define the meaning of the brand, while communities around several brands of the same product category define the meaning of a product category.Future research has to describe a brands’ position in these communities more precisely. This can happen by analyzing larger association databases or through target-specific large-scale data collection in several languages. In further research, the characteristics of the test participants must be taken into account, for example, their gender, age or consumer habits. A better understanding of communities in the mind contributes to the understanding of brands as psychological constructs, enabling the use of more effective brand management practices in the future.