Bimetallic NiCo2S4 Nanorod Cocatalyst Modified the Flower-Like Zn3In2S6 Microsphere for Visible-Light-Driven High-Efficiency Photocatalytic Hydrogen Production

Abstract

Establishing Schottky barriers is a key tactic for enhancing the separation of photogenerated charge carriers and improving photocatalytic efficiency. Herein, a self-assembled metal cocatalyst, NiCo₂S₄ nanorod, is loaded onto the flower-like Zn₃In₂S₆ microsphere via a hydrothermal method. Under visible light irradiation, the NiCo₂S₄/Zn₃In₂S₆ composite material achieves a peak H₂ production rate of 3436.72 μmol g⁻¹ h⁻¹ within 6 h, marking a 5.4 times greater increase compared to pristine Zn₃In₂S₆. This outperforms the maximum H₂ production rate of Pt/Zn₃In₂S₆-1% within the same 6-hour timeframe, which is 3323.05 μmol g⁻¹ h⁻¹. Additionally, the apparent quantum efficiency reaches 7.86% at 420 nm. The outstanding photocatalytic activity stems from the synergistic effects between the visible-light-active Zn₃In₂S₆ and the conductive cocatalyst NiCo₂S₄, facilitating spatial electrical promotion. In particular, the formation of a Schottky junction at the interface of NiCo₂S₄/Zn₃In₂S₆ enables prompt electron transfer to NiCo₂S₄ nanorods, preventing backflow and thereby promoting the efficient separation of photogenerated charge carriers. Finally, a plausible reaction mechanism is proposed, drawing from the electrochemical characterization results. Thus, this research provides a new approach for designing metal-semiconductor photocatalysts that are efficient in photocatalytic H₂ production through water splitting.