Multifunctional photocatalysts of Pt-decorated 3DOM perovskite-type SrTiO3 with enhanced CO2 adsorption and photoelectron enrichment for selective CO2 reduction with H2O to CH4

Herein, we prepared the multifunctional photocatalysts of Pt nanoparticles (NPs)-decorated 3D ordered macroporous (3DOM) perovskite-type SrTiO3 (Ptn/3DOM-SrTiO3). The slow light effect of 3DOM photocatalysts improves the absorption of incident light. Surface alkaline-earth-metal Sr component enhances the adsorption and activation for CO2. Supported Pt NPs can trap and gather excited photoelectrons derived from SrTiO3, and Pt-SrTiO3 heterojunction improves the separation of photogenerated carriers. Ptn/3DOM-SrTiO3 photocatalysts exhibited high-efficient photocatalytic performance for CO2 reduction to CH4 product. Among the catalysts, Pt2/3DOM-SrTiO3 catalyst shows the highest catalytic activity and selectivity, i.e., its formation rate of CH4 (26.7 μmol g−1 h−1) is 20-fold that of commercial P25, and its selectivity to CH4 product is 86.7%. The catalytic mechanism for selective CO2 photoreduction to CH4 is proposed: the adsorption property for CO2 and surface enrichment of photoelectrons are two rate-determining steps to improve selectively photocatalytic reduction of CO2 to CH4.