Strong interfacial coupling of Ni5P4/ZnCdS Schottky junction enhanced charge separation for boosting photocatalytic hydrogen evolution

Abstract

Constructing heterojunctions with high photogenerated carrier separation efficiency is an effective means to improve the performance of photocatalytic hydrogen production. In this work, a robust Ni 5 P 4 /ZnCdS Schottky junction was successfully constructed via strong interfacial coupling between chemically bonded porous Ni 5 P 4 nanoflowers and ZnCdS, significantly boosting interfacial charge separation and photocatalytic hydrogen evolution (PHE). Porous Ni 5 P 4 nanoflower was prepared by in situ low temperature phosphating calcination method, which can effectively prevent the aggregation of ZnCdS via its three-dimensional structure and provide abundant active and adsorption sites for PHE. In addition, chemically bonded Ni 5 P 4 and ZnCdS form tight electron transfer channels through Ni-S bonds at the Ni 5 P 4 /ZnCdS interface, accelerating the directional transfer of electrons at the interface and achieving better interface coupling. The Tafel slope indicates that Ni 5 P 4 /ZnCdS has excellent reaction kinetics. The electron transfer mechanism and Schottky heterojunction were elucidated through density functional theory (DFT) and in-situ XPS characterization. And the Schottky barriers at the Ni 5 P 4 /ZnCdS interface effectively prevent the recombination of photogenerated carriers, thereby improved the PHE activity. Consequently, the optimized 20 % Ni 5 P 4 /ZnCdS shows excellent PHE activity (34.92 mmol g −1 h −1 ) with high AQE of 13.56 % at 450 nm, which is 14.2 times higher than ZnCdS (2.46 mmol g −1 h −1 ). And exceptional photocatalytic stability of 20 % Ni 5 P 4 /ZnCdS was consistently maintained over multiple operational cycles. This work furnishes valuable strategy to construct Schottky junctions for enhancing PHE ability.