Fabrication of N/K-doped TiO2-Ag Nanospheres with Efficient Charge Transfer for Enhanced Photocatalytic CO2 Reduction into CH4

Solar-driven CO2 reduction into hydrocarbon fuels has a great potential for mitigating the issues of greenhouse effect and fossil energy crisis we are currently facing. It is a great challenge for visible-light-driven photocatalytic CO2 reduction into CH4 with high selectivity and conversion efficiency. Herein, we report a synthesis of N/K-doped TiO2 nanospheres with Ag nanoparticles decoration (N/K-TiO2-Ag) by a solvothermal method and study its photocatalytic CO2 reduction performance. It is found that the N/K-TiO2-Ag composite exhibits superior photocatalytic CO2 reduction into CH4 yield and selectivity than K-TiO2 and N/K-TiO2. Indeed, the N/K-TiO2-Ag-0.5 sample shows the highest CH4 yield with rate of 113.84 μmol g−1 h−1 and selectivity of CH4 (93.71%) under light irradiation. The enhancement might be attributed to the synergy of N/K doping and silver loading. In particular, the N/K doping and the Ag cocatalysts introducing triggered improvement of solar energy utilization and charge separation as well as Ag-induced SPR effect and the K+-induced redistribution of photogenerated charge carriers cooperatively promotes photocatalytic CO2 conversion into CH4. It is expected this work would offer a guide for rational design of K/TiO2-based photocatalyst for selectively converting CO2 into fuels.