Enhance photocatalytic CO2 reduction and biomass selective oxidation via sulfur vacancy-enriched S-scheme heterojunction of MoS2@GCN

Abstract

Photocatalytic CO2 reduction and biomass selective oxidation have considerable practical implications in addressing environmental challenges. However, developing efficient photocatalyst is the key to realize the mass-market applications. Herein, an MoS2@GCN S-scheme heterojunction, rich in sulfur vacancies (Sv), was fabricated by a dicyandiamide-blowing and calcination strategy using NH4Cl as the gas template. With the synergistic effects of Sv and the S-scheme charge migration mechanism, the 30%-Sv-MoS2@GCN demonstrated exceptional performance, showcasing a CO evolution rate of 68.3 μmol g−1 h−1 and a xylonic acid yield of 64.2%, without using any sacrificial agents. The formation of Sv was confirmed through electron paramagnetic resonance (EPR) analysis. The S-scheme charge transfer mechanism of the Sv-MoS2@GCN heterojunction was verified by in-situ X-ray photoelectron spectroscopy (XPS) spectra, EPR analysis, and density functional theory (DFT) calculations. This study establishes a framework for enhancing photocatalytic CO2 reduction and biomass selective oxidation by regulating charge transfer through sensible structural design.