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

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 (Delta G(H*)). Accordingly, the optimal Ni@NiSx-CdS photocatalyst delivers a remarkable photocatalytic H-2 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-H-2 energy conversion.

Automated summary

This study presents the fabrication of an amorphous-crystalline Ni@NiSx-CdS photocatalyst by assembling an amorphous Ni@NiSx cocatalyst onto CdS. The synergistic effects between the electronic coupling of the amorphous-crystalline interface and the variation of work function achieved improved performance of the photocatalyst in terms of photocatalytic H-2 production rate and quantum efficiency.