Engineering Cu surfaces for the electrocatalytic conversion of CO_2: Controlling selectivity toward oxygenates and hydrocarbons
Hahn, Christopher and Hatsukade, Toru and Kim, Youn-Geun and Vailionis, Arturas and Baricuatro, Jack H. and Higgins, Drew C. and Nitopi, Stephanie A. and Soriaga, Manuel P. and Jaramillo, Thomas F. (2017) Engineering Cu surfaces for the electrocatalytic conversion of CO_2: Controlling selectivity toward oxygenates and hydrocarbons. Proceedings of the National Academy of Sciences of the United States of America, 114 (23). pp. 5918-5923. ISSN 0027-8424. PMCID PMC5468660. https://resolver.caltech.edu/CaltechAUTHORS:20170522-125149776
In this study we control the surface structure of Cu thin-film catalysts to probe the relationship between active sites and catalytic activity for the electroreduction of CO_2 to fuels and chemicals. Here, we report physical vapor deposition of Cu thin films on large-format (∼6 cm^2) single-crystal substrates, and confirm epitaxial growth in the <100>, <111>, and <751> orientations using X-ray pole figures. To understand the relationship between the bulk and surface structures, in situ electrochemical scanning tunneling microscopy was conducted on Cu(100), (111), and (751) thin films. The studies revealed that Cu(100) and (111) have surface adlattices that are identical to the bulk structure, and that Cu(751) has a heterogeneous kinked surface with (110) terraces that is closely related to the bulk structure. Electrochemical CO_2 reduction testing showed that whereas both Cu(100) and (751) thin films are more active and selective for C–C coupling than Cu(111), Cu(751) is the most selective for >2e− oxygenate formation at low overpotentials. Our results demonstrate that epitaxy can be used to grow single-crystal analogous materials as large-format electrodes that provide insights on controlling electrocatalytic activity and selectivity for this reaction.
http://dx.doi.org/10.1073/pnas.1618935114 DOI Article
http://www.ncbi.nlm.nih.gov/pmc/articles/pmc5468660/ PubMed Central Article
http://www.pnas.org/lookup/suppl/doi:10.1073/pnas.1618935114/-/DCSupplemental Publisher Supporting Information
Hahn, Christopher 0000-0002-2772-6341
Hatsukade, Toru 0000-0001-9016-0929
Kim, Youn-Geun 0000-0002-5936-6520
Vailionis, Arturas 0000-0001-5878-1864
Higgins, Drew C. 0000-0002-0585-2670
Nitopi, Stephanie A. 0000-0001-6815-0628
Soriaga, Manuel P. 0000-0002-0077-6226
Jaramillo, Thomas F. 0000-0001-9900-0622
© 2017 National Academy of Sciences. Edited by Jean-Michel Savéant, Université Paris Diderot, Paris, France, and approved April 10, 2017 (received for review November 16, 2016). Published online before print May 22, 2017. We thank Dr. Jakob Kibsgaard and Dr. Karen Chan for their assistance in constructing the Cu surface structure models. Additional thanks go to the Stanford NMR Facility. Part of this work was performed at the Stanford Nano Shared Facilities (SNSF) and the Stanford Nanofabrication Facility (SNF), supported by the National Science Foundation under Award ECCS-1542152. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a Department of Energy (DOE) Innovation Hub, as follows: the development of electrochemical testing of Cu thin films was supported through the Office of Science of the US DOE under Award DE-SC0004993; the development of epitaxial growth was supported by the Global Climate Energy Project at Stanford University; the procurement of the physical vapor deposition chamber was supported by the DOE, Laboratory Directed Research and Development funding under Award DE-AC02-76SF00515. Author contributions: C.H., T.H., Y.-G.K., A.V., J.H.B., D.C.H., S.A.N., M.P.S., and T.F.J. designed research; C.H., T.H., Y.-G.K., A.V., J.H.B., D.C.H., and S.A.N. performed research; C.H., T.H., Y.-G.K., A.V., J.H.B., D.C.H., S.A.N., M.P.S., and T.F.J. analyzed data; C.H., T.H., Y.-G.K., A.V., J.H.B., D.C.H., S.A.N., M.P.S., and T.F.J. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission. This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1618935114/-/DCSupplemental.
JCAP
NSF ECCS-1542152
Department of Energy (DOE) DE-SC0004993
Stanford University UNSPECIFIED
Department of Energy (DOE) DE-AC02-76SF00515
carbon dioxide reduction; epitaxy; electrocatalysis; copper
Christopher Hahn, Toru Hatsukade, Youn-Geun Kim, Arturas Vailionis, Jack H. Baricuatro, Drew C. Higgins, Stephanie A. Nitopi, Manuel P. Soriaga, and Thomas F. Jaramillo Engineering Cu surfaces for the electrocatalytic conversion of CO2: Controlling selectivity toward oxygenates and hydrocarbons PNAS 2017 114 (23) 5918-5923; published ahead of print May 22, 2017, doi:10.1073/pnas.1618935114