Simultaneous co-Photocatalytic CO2 Reduction and Ethanol Oxidation towards Synergistic Acetaldehyde Synthesis.

Photocatalytic conversion of CO2 is of great interest but it often suffers sluggish oxidation half reaction and undesired by-products. Here, we report for the first the simultaneous co-photocatalytic CO2 reduction and ethanol oxidation towards one identical value-added CH3 CHO product on a rubidium and potassium co-modified carbon nitride (CN-KRb). The CN-KRb offers a record photocatalytic activity of 1212.3 µmol h-1 g-1 with a high selectivity of 93.3 % for CH3 CHO production, outperforming all the state-of-art CO2 photocatalysts. It is disclosed that the introduced Rb boosts the *OHCCHO fromation and facilitates the CH3 CHO desorption, while K promotes ethanol adsorption and activation. Moreover, the H+ stemming from ethanol oxidation is confirmed to participate in the CO2 reduction process, endowing near ideal overall atomic economy. This work provides a new strategy for effective use of the photoexcited electron and hole for high selective and sustainable conversion of CO2 paired with oxidation reaction into identical product.