Atomic-Level Interfacial Engineering of Zr-In2S3/g-C3N4 Z-Scheme Heterojunction for Enhanced Photocatalytic CO2 Reduction

Abstract

Photocatalytic CO2 reduction is severely limited by inefficient charge separation and weak interfacial electric fields in conventional semiconductor heterojunctions. Herein, we report the rational design and synthesis of stable heterojunction photocatalysts，combining 3D Zr-doped In2S3 and 2D g-C3N4 , through a hydrothermal route for enhancing CO2 reduction. The in-situ growth of Zr-In2S3 on g-C3N4 nanosheets formed an atomic-level coordination interface, characterized by Zr-N bonding, which creates an efficient electron-transfer pathway. This atomic-level synergy, combined with the favorable band alignment, generates a significantly intensified built-in internal electric field (IEF) across the heterojunction. The robust IEF drives the directional separation and migration of electrons among Zr-In2S3 and g-C3N4 , enhancing the Z-scheme separation efficiency of photogenerated carriers. Furthermore, the hierarchical architecture enhances CO2 adsorption and provides abundant active sites. Consequently, the optimized catalyst achieved CO2 to CH4 conversion rates of 49.87 μmol•g⁻¹ h⁻¹ and 12.90 μmol•g⁻¹ h⁻¹ under UV light irradiation, representing an 8.78-fold increase in CH4 production and a 2.32-fold increase in CO production compared to the pristine materials (Zr-In2S3 and g-C3N4). Density functional theory (DFT) calculations explicitly confirmed the charge transfer mechanism and quantified the critical role of the Zr-enhanced IEF in facilitating CO2 reduction kinetics. This study demonstrates that atomic-level interfacial engineering is a powerful strategy for amplifying the IEF in Z-scheme heterojunctions, enabling highly efficient solar fuel production.