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 CH3CHO product on a rubidium and potassium co-modified carbon nitride (CN-KRb). The CN-KRb offers a record photocatalytic activity of 1212.3 mu mol h(-1)g(-1) with a high selectivity of 93.3 % for CH3CHO production, outperforming all the state-of-art CO2 photocatalysts. It is disclosed that the introduced Rb boosts the *OHCCHO fromation and facilitates the CH3CHO 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.

Automated summary

A potassium and rubidium co-modified carbon nitride (CN-KRb) was reported for the simultaneous co-photocatalytic CO2 reduction and ethanol oxidation to produce the same product, CH3CHO. The CN-KRb showed record photocatalytic activity and high selectivity, with the involvement of rubidium and potassium. The study confirmed the participation of H+ from ethanol oxidation in the CO2 reduction process, achieving near ideal overall atomic economy. This work provides a new strategy for effective and sustainable conversion of CO2 into the same product through photoexcited electron and hole utilization.