Schottky heterojunction-mediated charge separation in ZnIn2S4/Cu for boosted photocatalytic CO2 reduction

Abstract

Photocatalytic reduction represents a promising and sustainable strategy for the resource-oriented conversion of CO₂, addressing both environmental pollution and energy scarcity challenges. However, its practical application is severely hindered by the low separation efficiency of electrons and insufficient active sites in conventional photocatalysts, resulting in unsatisfactory catalytic performance. Herein, copper nanoparticles (Cu NPs) were uniformly anchored onto the surface of ZnIn₂S₄ (ZIS) via a facile photoreduction approach, successfully constructing a ZnIn₂S₄/Cu Schottky heterojunction composite photocatalyst for efficient photoreduction of CO₂. A combination of comprehensive characterization techniques, including transmission electron microscopy, photo-electrochemical measurements, and density functional theory calculations, clearly demonstrates that the introduction of Cu NPs enables the formation of a Schottky barrier. This unique structural feature effectively promotes the separation and rapid migration of photogenerated charge carriers, thereby suppressing charge recombination and improving catalytic activity. Notably, the optimized ZnIn₂S₄/Cu composite exhibits a remarkable CO production rate of 17.5 µmol g⁻¹ h⁻¹, which is 4.86 times higher than that of pure ZIS. Collectively, this work not only provides a novel and feasible strategy for the rational design of high-performance, low-cost photocatalysts for CO₂ reduction but also offers valuable theoretical insights into the regulation of charge carrier dynamics in Schottky heterojunction-based photocatalytic systems.