Enhanced solar to hydrogen conversion via Ni addition to a few layered 2D/2D g-C3N4/ZnIn2S4 heterojunction

Abstract

The development of an earth-abundant, low-cost ultrathin “sheet-on-sheet” heterostructure, comprising few-layered g-C₃N₄ and ZnIn₂S₄ nanosheets (FCN/ZIS), demonstrates remarkable potential for diverse applications. This innovative heterostructure exhibits notable properties, including a porous FCN matrix enabling charge transfer cavities, one-directional migration of photogenerated charge carriers at the FCN/ZIS interface, and staggered gap band alignment promoting interfacial charge separation, resulting in exceptional photocatalytic hydrogen evolution reaction (HER) activity. Furthermore, the addition of a small amount of nickel salts into the reaction solution significantly enhances the HER activity, yielding a rate of 16.93 mmol h⁻¹ g⁻¹, representing a substantial improvement over pristine ZIS (2.17 mmol h⁻¹ g⁻¹) and FCN. Through comprehensive experimental and theoretical analyses, it was elucidated that the augmented solar-to-hydrogen conversion in Ni–FCN/ZIS was attributed to the effective charge carrier separation facilitated by the unique properties of the ultrathin “sheet-on-sheet” FCN/ZIS heterostructure, along with superior charge transportation facilitated by Ni salts within the reaction solution and active Ni sites, thereby significantly reducing the HER overpotential. This pioneering utilization of Ni salts within the FCN/ZIS system for photocatalytic hydrogen production holds promising prospects for advancing research in this domain.