Addressing Solar Photochemistry Durability with an Amorphous Nickel Antimonate Photoanode

Renewable generation of fuels using solar energy is a promising technology whose deployment hinges on the discovery of materials with a combination of durability and solar-to-chemical conversion efficiency that has yet to be demonstrated. Stable operation of photoanodes has been demonstrated with wide-gap semiconductors, as well as protected visible gap semiconductors. Visible photoresponse from electrochemically stable materials is quite rare. In this paper, we report the high-throughput discovery of an amorphous Ni-Sb (1:1) oxide photoanode that meets the requirements of operational stability, visible photoresponse, and appreciable photovoltage. X-ray absorption characterization of Ni and Sb establishes a structural connection to rutile NiSb₂O₆, guiding electronic structure characterization via X-ray photoelectron experiments and density functional theory. This amorphous photoanode opens avenues for photoelectrode development due to the lack of crystal anisotropy combined with its operational stability, which mitigates the formation of an interphase that disrupts the semiconductor-electrolyte junction.