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

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.