Dual MOFs template-directed fabrication of hollow-structured heterojunction photocatalysts for efficient CO2 reduction

Abstract

The hollow-structured C-In 2 O 3 @MO (MO = ZnO, Co 3 O 4 , and ZnCo 2 O 4 ) heterojunction photocatalysts are fabricated by the core–shell structured dual MOF template-directed strategy. The obtained photocatalysts exhibit high performance for CO 2 photoreduction, due to the suitable energy band matching structure and high solar light unilization. • A dual MOFs template-directed strategy for fabricating heterojunction photocatalysts is firstly developed. • A series of C-In 2 O 3 @MO (MO = ZnO, Co 3 O 4 , and ZnCo 2 O 4 ) heterojunctions are fabricated. • The sutiable energy matching and hollow structure of the C-In 2 O 3 @ZnCo 2 O 4 promotes CO 2 photoreduction activity. Developing efficient photocatalysts for CO 2 reduction into value-added chemical feedstocks is of significance. Heterojunction photocatalysts are promising candidates but still suffering from the insufficient electron-hole pair separation issues. Herein, a strategy that dual metal–organic frameworks (MOFs) template-directed fabrication of carbon-supported heterojunction, C-In 2 O 3 @MO (MO = ZnO, Co 3 O 4 , and ZnCo 2 O 4 ) with tunable band matching structure was developed. The resultant hollow- structured C-In 2 O 3 @ZnCo 2 O 4 shows high CO 2 reduction activity towards CO (44.1 μmol g 1 h −1 ) with a selectivity of 66%. The superior performance of this material could be ascribed to the suitable energy band matching and efficient internal charge transfer on p-n heterojunction, which facilitates electron-hole separation. Meanwhile, the hollow cavity not only improved light-harvesting capability through multiple light reflection and scattering in the internal voids but also provided large surface area for exposing active sites to promoting the activation of CO 2 . This study thus proposes a feasible approach to adjust the heterojunction structure of photocatalysts to achieve efficient CO 2 reduction reaction.