Modulating electronic structure and sulfur p-band center by anchoring amorphous Ni@NiSx on crystalline CdS for expediting photocatalytic H2 evolution

Abstract

Photocatalytic water splitting is a prospective approach to address the energy and environmental challenges. Herein, an amorphous Ni@NiSx cocatalyst has been fabricated and simultaneously assembled onto CdS to form amorphous-crystalline Ni@NiSx-CdS photocatalyst via a partial reduction strategy. Comprehensive experiments and theoretical calculations demonstrate that the synergistic effects between the electronic coupling of amorphous-crystalline interface and the gradient work function variation induced by Ni nanocluster encapsulation achieve the deeper downshift of the S p-band center to optimize H* intermediate adsorption, enhance charge extraction ability though Schottky junction and lower H* adsorption Gibbs free energy (ΔGH*). Accordingly, the optimal Ni@NiSx-CdS photocatalyst delivers a remarkable photocatalytic H2 production rate of 78.7 mmol·g−1·h−1 with an apparent quantum efficiency (AQE) of 36.74% at 420 nm, which is approximately 18.3 and 1.5 times than that of CdS and NiSx-CdS, respectively. This work offers a novel insight into the development of amorphous nanocomposite cocatalysts for promoting solar-to-H2 energy conversion.