In-situ generation of Bi0 NCs and vacancies on Bi-CTS/BiOBr heterostructures accelerate electron transfer for promoting photocatalytic reduction of CO2

Abstract

Developing high-efficiency photocatalysts for CO2 conversion remains a challenge. Herein, S-scheme Bi-Cu3SnS4/BiOBr heterojunction with S, O defective vacancies was successfully prepared by hydrothermal process and NaBH4 reduction method. Characterization results showed that the Cu3SnS4 nanoparticles were uniformly dispersed onto the BiOBr nanosheets, with Bi0 nanoclusters (NCs) serving as a bridge between the BiOBr and Cu3SnS4. The S-scheme heterojunction was demonstrated via ultraviolet photoelectron spectrometer (UPS) work function. The surface plasma resonance (SPR) effect of Bi0 NCs, the internal electric field (IEF) and S, O defects coregulation of Fermi level equilibrium enhanced light utilization and facilitated photogenerated carriers’ separation, resulting in superior photocatalytic activity. Under visible light illumination, the Bi-Cu3SnS4/BiOBr(30) achieved CO yield of about 50.13 μmol·g−1·h−1 within 120 min, which was 3.5 times of pristine Cu3SnS4 (15.6 μmol·g−1·h−1). Moreover, it exhibited the highest incident photon-electron conversion efficiency (10.58% at 380 nm). This study could provide a reference for designing efficient S-scheme heterojunctions for photocatalytic reduction of CO2.