Enhanced visible light photocatalytic activity of BiFeO3-ZnO p-n heterojunction for CO2 reduction

Highlights: • Photocatalytic ability of BiFeO₃-ZnO was investigated for conversion CO₂ and CH₄. • Photoactivity was assigned to effect of p-n heterojunction and vis-light sensitivity of BiFeO₃. • Increasing BiFeO₃ content led to an increase in charge separation and visible light activity. • The highest photocatalytic efficiency was achieved by composite sample with molar ratio 1:1. - Abstract: The visible light photocatalytic ability of bismuth ferrite-zinc oxide composites with different molar ratios was investigated for conversion of CO₂ in the gas phase. The catalysts were successfully synthesized by hydrothermal method, and characterized by XRD, EDS, FESEM, UV–vis, and PL analyses. Also, the gaseous products were identified by FTIR technique. The FESEM illustrated the well crystalline particles of ZnO and BiFeO₃. The UV–vis and PL analyses revealed that by increasing BiFeO₃ content, the composites showed higher optical response in visible region and higher efficiency of charge separation, respectively. Compared with the pure ZnO and BiFeO₃, which had poor performances under visible light irradiation, the as-synthesized photocatalysts showed the enhanced visible light photocatalytic activity for CO₂ reduction. The highest photocatalytic conversion of CO₂, 21%, was achieved by the as-synthesized photocatalyst with molar ratio of 1:1 under visible light. The enhanced visible light photocatalytic activity of BiFeO₃-ZnO was assigned to the synergistic effect of p-n heterojunction and visible light sensitive property of perovskite structure of BiFeO₃.