Engineering of visible light-activated ZnIn₂S₄/N-rGO S-scheme heterojunction photocatalyst for H₂ generation

The design of S-scheme heterojunction photocatalysts emerges as high-profile candidates for hydrogen (H₂) generation. Herein, by integrating heterojunction creation and heteroatom-doping approaches, ZnIn₂S₄/N-rGO photocatalyst is synthesized using a hydrothermal process. Crystallinity, morphology, surface area, light absorption, interfacial interaction, and charge separation and migration properties of ZnI₂S₄/Nitrogen-doped reduced graphene oxide (ZnIn₂S₄/N-rGO) are analytically explored to authenticate its successful construction. Consequently, the H₂ generation performance of ZnIn₂S₄/N-rGO reached 2847 µmolh^{-1 g-1} under visible light illumination, which is about 9.7 and 1.6 times as high as that of ZnIn₂S₄ and ZnIn₂S₄/rGO, respectively, with efficient stability. ZnIn₂S₄/N-rGO exhibits enhancement in the optical response, promotes the surface area, and improves separation and transport of photoexcited electron/hole pairs, attributing to higher H₂ generation activity. The S-scheme charge migration mechanism is authenticated through EPR spectra. The current study not only signifies that ZnIn₂S₄/N-rGO is an excellent photocatalyst for H₂ generation but also offers a route to develop outstanding and stable photocatalysts by combining heterojunction creation and heteroatom-doping approaches.