Hydrothermally decorated robust bimetallic sulfides with heterojunction interfaces for efficient hydrogen generation

Abstract

Bimetallic semiconductor metal sulphides are promising for harnessing light energy. In this report, a hydrothermally decorated robust ZnO/ZnS/NiS (ZSN) ternary composite was synthesized and employed in photocatalytic H2 generation. The structurally defined ZnS/NiS on ZnO nanorods have been observed as efficient visible light driven proton reduction system due to its multiple accessible active sites. Benefitting from the synergetic effects between highly active, ZnS and NiS, the ternary composite ZSN exhibited significantly improved performance of H2 generation with a rate of 8471 μmol g−1h−1 and AQE of ∼5.5% under solar irradiation. This design in ZSN enables effective transfer of electrons from ZnS to NiS active sites leading to 29 times and 3.4 times increase in hydrogen production and current density when compared with pristine ZnO photocatalyst, respectively. The photocurrent density and transient photocurrent curve show rapid charge transfer as well as the unique electron transfer paths through the contact surface, resulting in efficient charge separation. DFT and photoelectrochemical studies reveal higher HER activity due to the augmented electric field at the dual-interfaces between NiS and ZS complex.