Photocorrosion of polyaniline-ZnS–ZnO photoelectrode for water splitting

•Comparative photocorrosion for PANI/ZnS/ZnO and ZnS/ZnO were studied.•Photocurrents of the ZnS/ZnO were ~78% reduced after photocorrosion tests.•We report anti-photocorrosion effects of both the PANI layer and the band alignment.•They were caused by effective removal of photo-excited electrons-holes in ZnS/ZnO. Photoelectrodes of polyaniline-coated ZnS film/ZnO nanorods (NRs) for water splitting were evaluated for their photocorrosion behavior. Their microstructure transition and photocatalytic properties were systematically investigated using cyclic voltammetry with light illumination. In photoelectrodes without polyaniline (PANI) coating after 20-cycle tests, photocurrent was reduced by approximately 78%. The ZnO NRs were almost completely photocorroded. On the other hand, PANI-coated photoelectrodes showed no reduction of photocurrent, and no photocorrosion of the ZnS/ZnO structures. Thus, it can be confirmed that the PANI layer has a photocorrosion prevention effect. This effect can be explained by the self-redox potential levels and band alignment of each constituent material relative to the redox potential for water splitting. We report that it is important to prevent the accumulation of photo-excited electrons and holes in photocatalysts. It appears that the PANI-coated ZnS/ZnO structures have sufficient band alignment to prevent this accumulation.