A Z-scheme ZnFe2O4/RGO/In2O3 hierarchical photocatalyst for efficient CO2 reduction enhancement

Abstract

Indium oxide (In₂O₃)-based photocatalysts have great potential in photocatalytic CO₂ reduction. Nevertheless, their photocatalytic activity is inhibited by rapid electron–hole recombination. Hence, a novel Z-scheme ternary hierarchical ZnFe₂O₄/RGO/In₂O₃ photocatalyst is fabricated for photocatalytic conversion of CO₂ to CO and CH₄. The CO production rate reaches up to 35.4 μmol g⁻¹ under 4 h of illumination using a 20ZFO/10RGO/IO catalyst, which is 3.9 times and 9.8 times higher than those using bare In₂O₃ and bare ZnFe₂O₄, respectively. The CH₄ production rate is 7.8 μmol g⁻¹, which is 4.3 fold and 2.4 fold higher, respectively, compared to those from bare In₂O₃ and bare ZnFe₂O₄. The enhancement of photocatalytic CO₂ reduction was ascribed to a Z-scheme mechanism of the hierarchical catalysts by introducing RGO in-between In₂O₃ and ZnFe₂O₄ to promote charge separation and realize efficient utilization of the high-energy electrons and holes. The oxygen-defect of ZnFe₂O₄ also facilitates the adsorption and activation of CO₂. This work provides new insights to design ternary In₂O₃-based hierarchical photocatalysts with a rational Z-scheme photocatalytic mechanism to improve the CO₂ conversion efficiency.