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Title: Water oxidation by size selected Co 27 clusters supported on Fe 2O 3

The complexity of the water oxidation reaction makes understanding the role of individual catalytic sites critical to improving the process. Here, size-selected 27-atom cobalt clusters (Co 27) deposited on hematite (Fe 2O 3) anodes were tested for water oxidation activity. The uniformity of these anodes allows measurement of the activity of catalytic sites of well-defined nuclearity and known density. Grazing incidence X-ray absorption near-edge spectroscopy (GIXANES) characterization of the anodes before and after electrochemical cycling demonstrates that these Co 27 clusters are stable to dissolution even in the harsh water oxidation electrochemical environment. They are also stable under illumination at the equivalent of 0.4suns irradiation. The clusters show turnover rates for water oxidation that are comparable or higher than those reported for Pd- and Co-based materials or for hematite. The support for the Co 27 clusters is Fe 2O 3 grown by atomic layer deposition on a Si chip. We have chosen to deposit a Fe2O3 layer that is only a few unit cells thick (2nm), to remove complications related to exciton diffusion. We find that the electrocatalytic and the photoelectrocatalytic activity of the Co 27/Fe 2O 3 material is significantly improved when the samples are annealed (with the clustersmore » already deposited). Lastly, given that the support is thin and that the cluster deposition density is equivalent to approximately 5% of an atomic monolayer, we suggest that annealing may significantly improve the exciton diffusion from the support to the catalytic moiety.« less
ORCiD logo [1] ;  [1] ;  [2] ;  [2] ;  [3] ;  [3] ;  [4] ;  [4] ;  [5]
  1. Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division; Argonne National Lab. (ANL), Argonne, IL (United States). Argonne-Northwestern Solar Energy Research (ANSER) Center
  2. Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division
  3. Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division
  4. Argonne National Lab. (ANL), Argonne, IL (United States). X-Ray Sciences Division
  5. Argonne National Lab. (ANL), Argonne, IL (United States). Nanoscience and Technology Division
Publication Date:
Grant/Contract Number:
AC02-06CH11357; SC0001059
Accepted Manuscript
Journal Name:
Additional Journal Information:
Journal Volume: 9; Journal Issue: 20; Journal ID: ISSN 1864-5631
ChemPubSoc Europe
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Fe2O3; electrocatalysis; photoelectrocatalysis; subnanometer cobalt cluster; water oxidation
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1356628