Enhanced Multi-Carbon Selectivity Via Tandem CO2 Electroreduction

Abstract

Electrifying chemical production is a potential approach to decarbonizing the chemical industry. Currently, 21% of the global greenhouse gas emissions come from the industry sector, while chemical manufacturing accounts for the largest share of industrial carbon emissions1. The electrochemical processes, when powered by renewable electricity, have lower carbon footprints than conventional thermochemical routes. The rapid development of renewable energy provides opportunities for electrifying chemical production and decarbonizing the chemical industry. Among these, electrochemical CO2 reduction reaction (CO2RR) attracted much attention as a potential pathway for carbon utilization and sustainable chemical production. In this presentation, I would like to present a tandem CO2 electroreduction scheme for multicarbon production. A molecular tuning strategy is applied to tune the intermediate binding energy and thus enhance the CO selectivity in the first step2. Then CO2 and CO electroreduction to C2+ products in alkaline conditions are compared, with particular emphasis on carbonate formation and carbon efficiency (i.e., the amount of carbon ended in the desired products divided by the total amount of CO2 consumed)3. The conclusion is that CORR shows specific advantages over CO2RR in the aspects of C2+ selectivity, stability, carbon efficiency, and single-pass conversion. Then oxide-derived Cu plates are chosen for the second step in tandem reduction, which shows a C2+ Faradaic efficiency of 83% at -0.59 V vs RHE. Lastly, we further extend our tandem system to electrocatalytic–thermocatalytic reaction for CO2 conversion to C3 oxygenate4. A 25 cm2 membrane electrode assembly device is coupled with a thermochemical hydroformylation reactor to produce 1-propanol and propanal. A total C3 oxygenate selectivity of ~18% is achieved in the tandem reaction.