Self-assembled spherical In2O3/BiOI heterojunctions for enhanced photocatalytic CO2 reduction activity

The development of low-cost, wide-wavelength-response-range high-efficiency photocatalysts is important to promote the separation of electron-hole pairs and the reduction of CO 2 to high-caloric-value hydrocarbons. Recently, BiOX has received much attention due to its excellent light absorption properties, unique tetragonal layered structure, and proper band gap. However, BiOX photocatalysts still suffer from rapid photogenerated electron-hole pair recombination rate and low product yield. It is imperative to construct effective heterojunction photocatalysts to overcome the above drawbacks. Herein, In 2 O 3 /BiOI with type II heterojunctions were successfully prepared by solvothermal methods for the photoreduction of CO 2 . The optimized BI-10 showed the highest photocatalytic yields of 11.98 μmol g −1 h −1 and 5.69 μmol g −1 h −1 for CO and CH 4 , respectively. The yields of CO were 5.3 and 4.2 times higher than those of pure BiOI and pure In 2 O 3 , respectively, The yields of CO were 5.3 and 4.2 times higher than those of pure BiOI and pure In2O3, respectively, as well as the yields of CH 4 were 2.1 and 1.9 times higher than those of pure BiOI and pure In 2 O 3 , respectively. This can be attributed to the close contact between In 2 O 3 and BiOI to form a type II heterojunction, which expands the spectral range of the photoreaction and promotes efficient charge separation and transfer at the heterojunction interface. This work can provide a reference for catalyst modification, which can be widely adopted in photocatalysis. • A spherical-nanosheet structure type II heterostructure of In 2 O 3 /BiOI was successfully synthesized. • The optimized binary composite In 2 O 3 /BiOI −10 % exhibited high photocatalytic activity and stability. • The optimized binary composites showed CO and CH 4 yields of 11.98 μmol g −1 h −1 and 5.69 μmol g −1 h −1 , respectively. • Possible mechanisms for charge transfer and photocatalytic reduction of CO 2 to CO and CH 4 reactions are proposed.