Stable photoelectrochemical salt-water splitting using the n-ZnSe/n-Ag8SnS6 photoanodes with the nanoscale surface state capacitances

A systemic analysis of ternary silver-tin sulphide (ATS), binary zinc selenide (ZnSe) and their heterogeneous junction photoanodes (ZnSe/ATS) were carried out in order to prepare a photoelectrode for salt-water splitting with the stable PEC performance. From the EIS analysis of each sample, we can find that the accumulation of holes in the surface states resulted in the photocorrosion of ATS samples in electrolyte and few amounts of photo-excited carriers in the ZnSe sample resulted in the low PEC performances. We designed a new n-n type heteogeneous junction as the photoelectrode for the salt-water splitting process. The PEC performance of the heterogeneous ZnSe/ATS photoelectrode with the ZnSe as the outer layer and ATS as the inner layer as the photoelectrode for salt-water splitting was then examined. The so-called Z-scheme took place at the surface states of ZnSe/ATS photoelectrode, which resulted in the better charge separation rate of photo-excited carriers and good PEC salt-water splitting efficiency than those for the ATS and ZnSe semiconductor under light irradiation.134