Constructing Co–S interface chemical bonds over Co@NC/ZnIn2S4 for an efficient solar-driven photocatalytic H2 evolution

Abstract

Developing novel photocatalysts with an intimate interface and sufficient contact is significant for the separation and migration of photogenerated carriers. In this work, a novel Co@NC/ZnIn₂S₄ heterojunction with a strong Co–S chemical bond was formed at the interface between Co@NC and ZnIn₂S₄, which accelerated charge separation. Meanwhile, the recombination of the electron–hole pairs was further restricted by the Co@NC/ZnIn₂S₄ Schottky junction. The Co@NC (5 wt%)/ZnIn₂S₄ composite exhibited an H₂ evolution rate of 33.3 μmol h⁻¹, which is 6.1 times higher than that of the pristine ZnIn₂S₄, and Co@NC/ZnIn₂S₄ showed excellent stability in the photocatalytic water splitting reaction. Its apparent quantum yield reached 38% at 420 nm. Furthermore, the Kelvin probe test results showed that the interfacial electric field formed as the driving force for interface charge transfer was oriented from Co@NC to ZnIn₂S₄. In addition, the Co–S bond as a high-speed channel facilitated the interfacial electron transfer. This work reveals that in situ formed chemical bonds will pave the way for designing high-efficiency heterojunction photocatalysts.