Plasmon-induced hole-depletion layer on p-n heterojunction for highly efficient photoelectrochemical water splitting.

The photoelectrocatalytic (PEC) water splitting efficiency of semiconductor photoelectrodes is mainly limited by the effective separation and transfer of photogenerated charges. Zinc indium sulfide-cuprous oxide (ZnInS-CuO) p-n heterojunction is constructed to enhance the PEC properties of ZnInS. The nickel hydroxide iron oxide (NiFeOOH) layer on the surface of the heterojunction can be used as a hole depletion layer under the induction of plasmon resonance of the most surface silver (Ag) (the holes transferred from CuO valence band to NiFeOOH layer can be excited by Ag to produce hot electron consumption, which makes the last remaining hot holes participate in the water oxidation reaction) to further promote the carrier separation and transfer. The results exhibit that ZnInS/CuO/NiFeOOH/Ag photoelectrode with dramatically enhanced photocurrent density of 1.22 mA/cm at 1.23 V versus the reversible hydrogen electrode (V), which is 9.4 times higher than the pure ZnInS. This work provides a promising concept to design photoelectrodes efficiently in PEC water splitting.