Revisiting Pt/TiO2 photocatalyst in the thermally assisted photocatalytic reduction of CO2
The artificial photosynthesis by semiconductor oxide photocatalysis is presently challenging due to low CO2 conversion rates and poor product selectivity. To promote CO2 reduction, Pt/TiO2 has been deemed as a classical photocatalyst. In this work, we restudy Pt/TiO2 in a case of thermally-assisted photocatalytic reduction of CO2 and reveal a different story between photocatalysis and photothermal catalysis. By taking disordered Pt/TiO2-x as an example, it is not impressive for CO2 conversion via photocatalysis at 298 K. However, when the system temperature is increased to 393 K, CO2 conversion rate is significantly enhanced by a factor of 155 referred to pristine TiO2 and a high selectivity of CH4 of 87.5% is surprisingly achieved. Thermal coupled photocatalysis discover a promoted evolution of H2 side product over Pt (4.06 nm)/TiO2 and whereas a promoted H2 splitting over Pt (2.33 nm)/TiO2, which is seldom observed in conventional Pt/TiO2 photocatalysis. The synergy of improved charge separation at Pt/TiO2-x interface induced by surface disordering and accelerated H2 consumption nearby smaller Pt nanoparticles by thermal assistance are believed critically important for simutaneous enhancement of CO2 conversion rates and CH4 product selectivity. This study inspires revisiting not only Pt/TiO2 but also reactivating other silent semiconductor oxide photocatalyst in thermal-assisted photocatalysis.