Unassisted solar water splitting using a Cu2O/Ni(OH)2-ZnO/Au tandem photoelectrochemical cell

A tandem photoelectrochemical (PEC) cell consisting of a Cu2O/Ni(OH)2 photocathode and a ZnO/Au photoanode was investigated for unassisted solar water splitting. It was found that the two photoelectrodes were optically matched in UV and visible range, according to the absorbed luminous flux. Compared with the bare Cu2O photocathode, the Cu2O/Ni(OH)2 photocathode had larger photocurrent and smaller onset potential, because the Ni(OH)2 electrocatalysts reduced charge recombination and the overpotential for hydrogen evolution. The tandem PEC cell achieved a photoconversion efficiency of about 0.20% under 1 sun illumination. The results indicate that metal oxide semiconductors synthesized via facile and scalable solution methods are promising photoelectrode materials for unassisted solar water splitting.