Fabricated S-scheme BiOBr/Cu2O heterojunction photocatalyst for adjusting conversion of CO2 to CH4

Abstract

The preparation of heterojunction photocatalysts with staggered energy band structures and proper interfacial contacts is an effective way to improve CO2 conversion. This study adopted a simple hydrothermal method to form Cu2O on the surface of BiOBr, and s scheme BiOBr/Cu2O heterojunctions with close contacts were constructed. The rate of CO2 reduction over the catalyst was tested in a gas-solid reactor simulating sunlight. The results show that the BiOBr/Cu2O composite moderately yields CH4 with an efficiency of 22.78 μmol g−1h−1 for conversion from CO2 to CH4 in visible light, while pure BiOBr yields only CO. In addition, Transient photocurrent response, Electrochemical impedance spectroscopy, and Photoluminescence measurements demonstrated that the BiOBr/Cu2O had a strong photogenerated carrier transfer and separation and high photo-availability, while key intermediates favoring CH4 yield were found by in situ IR. Finally, the possible photocatalytic mechanism was explored based on the energy band structures of BiOBr and Cu2O in the characterization.