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Published September 1, 2016 | public
Journal Article

Operando Analyses of Solar Fuels Light Absorbers and Catalysts

Abstract

Operando synchrotron radiation photoelectron spectroscopy (SRPES) in the tender X-ray energy range has been used to obtain information on the energy-band relations of semiconductor and metal-covered semiconductor surfaces while in direct contact with aqueous electrolytes under potentiostatic control. The system that was investigated consists of highly doped Si substrates that were conformally coated with ∼70 nm titania films produced by atomic-layer deposition. The TiO2/electrolyte and the Si/TiO2/Ni electrolyte interfaces were then analyzed by synchrotron radiation photoelectron spectroscopy. The PES data provided a determination of the flat-band position and identified regions of applied potential in which Fermi level pinning, depletion, or accumulation conditions occurred. Operando X-ray absorption spectroscopy (XAS) techniques were additionally used to investigate the properties of heterogeneous electrocatalysts for the oxygen-evolution reaction. Operando XAS including the pre-edge, edge and EXAFS regions allowed the development of a detailed picture of the catalysts under operating conditions, and elucidated the changes that in the physical and electronic structure of the catalyst that accompanied increases in the applied potential. Specifically, XAS data, combined with DFT studies, indicated that the activity of the electrocatalyst correlated with the formation of Fe dopant sites in γ-NiOOH.

Additional Information

© 2016 Elsevier Ltd. Received 11 December 2015, Revised 31 May 2016, Accepted 1 June 2016, Available online 6 June 2016. This work was supported by the Office of Science of the U.S. Department of Energy (DOE) through award no. DE-SC0004993 to the Joint Center for Artificial Photosynthesis. The Advanced Light Source acknowledges support by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract no. DE-AC02-05CH11231. XAS data collection was carried out at Stanford Synchrotron Radiation Lightsource, a National User Facility operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences. Computational work was carried out through NERSC computational resources under DOE Contract No. DE-AC02-05CH11231.

Additional details

Created:
August 22, 2023
Modified:
October 20, 2023