Highly Enhanced Visible-Light-Driven Photoelectrochemical Performance of ZnO-Modified In 2 S 3 Nanosheet Arrays by Atomic Layer Deposition

Photoanodes based on In 2 S 3 /ZnO heterojunction nanosheet arrays (NSAs) have been fabricated by atomic layer deposition of ZnO over In 2 S 3 NSAs, which were in situ grown on fluorine-doped tin oxide glasses via a facile solvothermal process. The as-prepared photoanodes show dramatically enhanced performance for photoelectrochemical (PEC) water splitting, compared to single semiconductor counterparts. The optical and PEC properties of In 2 S 3 /ZnO NSAs have been optimized by modulating the thickness of the ZnO overlayer. After pairing with ZnO, the NSAs exhibit a broadened absorption range and an increased light absorptance over a wide wavelength region of 250–850 nm. The optimized sample of In 2 S 3 /ZnO-50 NSAs shows a photocurrent density of 1.642 mA cm −2 (1.5 V vs. RHE) and an incident photon-to-current efficiency of 27.64% at 380 nm (1.23 V vs. RHE), which are 70 and 116 times higher than those of the pristine In 2 S 3 NSAs, respectively. A detailed energy band edge analysis reveals the type-II band alignment of the In 2 S 3 /ZnO heterojunction, which enables efficient separation and collection of photogenerated carriers, especially with the assistance of positive bias potential, and then results in the significantly increased PEC activity.