One-pot electrochemical organic wastewater oxidation coupled with simultaneous CO2 conversion to fuel in the “CO2-depleted” environment

To tackle the escalating problems of organic wastewater pollution and CO 2 emissions, we have developed a long-term operational electrocatalytic device for the one-pot electrochemical conversion of organic pollutants (using C 3 H 8 O 3 as a model compound) into liquid fuels. Commercial Pt/Ti and Sn served as the anode and cathode, respectively, with current density adjusted by varying the anolyte salt concentration. Experimental results show that the CO 2 proportion in the anode gas is low (<7 %), creating a “CO₂-depleted environment (2.6–6.6 % v/v )” in the cathode chamber. Surprisingly, formate can also be produced and the Carbon Utilization Efficiency (CUE) exceeds 80 %, despite the Faraday efficiency for formate (FE HCOO - ) consistently remaining below 2 % due to insufficient CO 2 supply from organic wastewater oxidation. While increased current density can boost CO 2 production, it concurrently exacerbates OH- accumulation, leading to a decrease in CUE, which necessitates finding an optimal balance between the two factors. Density functional theory (DFT) calculations reveal that increased CO 2 production in a “CO 2 -depleted” environment effectively enhances CO 2 adsorption energy on Sn and increases the reaction current density. This work reveals that the critical factor in enhancing FE HCOO - is identifying the optimal balance between anode CO₂ generation and cathode CO₂ utilization by adjusting current density, thus offering theoretical insights for targeted electrode fabrication and operational parameter optimization.