In Situ Self-Assembled ZIF-67/MIL-125-Derived Co3O4/TiO2 p–n Heterojunctions for Enhanced Photocatalytic CO2 Reduction

Photocatalytic CO2 reduction to carbon fuels is regarded as an ideal and sustainable way to provide clean energy and solve environmental crisis. Herein, a p-n Co3O4/TiO2 heterojunction photocatalyst was synthesized by one-step pyrolysis of self-assembly ZIF-67/MIL-125, which was used in photocatalytic CO2 reduction for the first time. Co3O4 nanocages were highly dispersed on the surface of TiO2 nanoplates with an intimate contact. The optimal Co3O4/TiO2 exhibited a significantly enhanced CO evolution rate of 1256 μmol g-1 h-1 under simulated solar light, which was 2.4 times higher than that of pure Co3O4. The high photocatalytic performance of Co3O4/TiO2 was attributed to its enriched active sites and formed p-n heterojunctions. According to the electrocatalytic measurements, the possible mechanism and photoinduced charge transfer process were discussed in detail. We believe that this research provides a facile and efficient approach to fabricate MOF-derived heterojunction photocatalysts for CO2 reduction.