Potential-dependent phase stability and trapped-electrons origin in copper oxide-based photocathodes for water splitting

This is the authors' abstract. We don't add key points for this paper.

Operando XAS studies in the field of photoelectrochemistry are quite scarce and are mostly devoted to composite systems, rather than to pure semiconductors. However, improving the knowledge of the primary photocatalytic processes occurring in semiconductors, e.g. charge generation, trapping and recombination is crucial to improve the performances of the photoactive materials. In this work, we report a study on the behavior of copper oxide-based photocathodes for hydrogen generation in water splitting. The phase composition of the materials in pristine conditions and after photocorrosion was investigated also considering the role of the applied potential in the dark and under illumination. The fate of the photogenerated carriers during the water splitting reaction was investigated by employing differential XANES spectra in dark and light. After illuminating, the photogenerated electrons can be involved in the CuO reduction as well as the H 2 production. The charge transfer calculated by CV corresponds to the sum of the electrons that reduce CuO, as measured by FEXRAV, and the electrons utilized for H 2 production. • Copper oxide is a promising photocathode for photoelectrochemical water splitting. • Improving the knowledge of photocatalytic processes. • Use of FEXRAV and cyclic voltammetry, at the same time, to investigate the process. • Operando differential light-dark (Δ μ ) XANES measurements to define the powder stability.