Strong photo-thermal coupling effect boosts CO2 reduction into CH4 in a concentrated solar reactor

This study is dedicated to solving the problems of low energy utilization and low yield in the conventional photocatalytic CO2 reduction process. Herein, we constructed a novel concentrated solar (light) reactor and enabled the titanium foam-based monolithic photocatalyst TF@TNT/0.4CoO(x-)0.1CuO to improve the solar en-ergy utilization efficiency and CO2 conversion rate by concentrating light and its thermal effect. We found that the yield of CH4 increased up to 220 times (from 0.53 mu mol/cm(2) to 116.4 mu mol/cm(2)) when the light intensity of the reactor was increased from 400 mW/cm(2) to 4266 mW/cm(2) (10.6 times). Meanwhile, the solar-to-fuel con-version efficiency was improved up to 0.35% in the concentrated solar (light) reactor. We further investigated the origin of the photothermal coupling effect with concentrated light through the electrochemical and photo-chemical measurements. It shows that the concentrated light can further lower the reaction barrier (from 41.62 to 31.51 kJ/mol) and the induced photothermal coupling effect could significantly increase the yield. This provides a valuable strategy for the efficient and environmentally friendly utilization of CO2 using solar energy.