Efficient photothermal catalytic CO2 reduction to CH3CH2OH over Cu2O/g-C3N4 assisted by ionic liquids

Abstract Photocatalytic CO2 reduction is a potential way to address simultaneously environmental pollution and energy shortage. However, the difficulties of CO2 activation and C C coupling lead to quite low conversion efficiency of CO2 to C2 products. In this study, we constructed Cu2O/g-C3N4 heterojunction for photocatalytic CO2 reduction to ethanol by coupling thermal field and ionic liquids (ILs). The ethanol rate reached 0.71 mmol·g−1·h−1 over Cu2O/g-C3N4 under photothermalcatalysis, which is 1.89 times that of photocatalysis and 7.05 times that of thermal catalysis. The temperature enhanced thermal motion of the radical, which promotes the formation of ethanol through the ·CH3 dimerization. The 1-aminopropyl-3-methylimidazolium bromide ILs shows superior CO2 reduction performance with a high current density (21.3 mA·cm−2) than KHCO3 electrolyte (12.8 mA·cm−2). The overpotential is reduced by 0.34 V, which accelerates CO2 reduction by reducing polarization. It is found that the ILs played a key role in suppressing H2O reduction and increasing ethanol yield in this photothermalcatalytic strategy.