The CuS-coated CuO nanostructures grown by ion exchange reaction for efficient photoelectrochemical water splitting

Abstract

CuO is a promising solar photocathode for hydrogen production. However, it suffers serious photocorrosion in the electrolyte, which hinders the efficiency of photoelectrochemical (PEC) water splitting. In the study, Cu(OH)2 nanowires were in situ grown on copper foils through a straightforward wet chemical oxidation process, followed by annealing in air to synthesize CuO photocathode. To enhance their performance, the surface of CuO photocathode was modified by loading CuS with the ion exchange reaction (IER). Under AM 1.5 G, the CuO photocathode modified by CuS showed a significant improvement in the photo-current density, achieving the highest photo-current density was −4.83 mA·cm−2 at 0 V vs. RHE, which was far superior to the photo-current density (-2.02 mA·cm−2) of pristine CuO photocathode at the same potential. Furthermore, the maximum applied bias photon-to-current efficiency (ABPE) of the CuO/CuS photocathode is 0.77 %, which is superior to that of pristine CuO (0.24 %). The enhanced PEC performance of CuO/CuS photocathode is attributed to the improved light absorption and the efficient separation of photogenerated electron-hole pairs.