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 (ZnIn2S4-Cu2O) p-n heterojunction is constructed to enhance the PEC properties of ZnIn2S4. 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 Cu2O 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 ZnIn2S4/Cu2O/NiFeOOH/Ag photoelectrode with dramatically enhanced photocurrent density of 1.22 mA/cm2 at 1.23 V versus the reversible hydrogen electrode (VRHE), which is 9.4 times higher than the pure ZnIn2S4. This work provides a promising concept to design photoelectrodes efficiently in PEC water splitting.