Enabling direct flue gas electrolysis by clarifying impurity gas effects on CO2 electroreduction

The direct electroreduction of CO2 from multicomponent flue gas into valuable chemicals has attracted extensive interest owing to its contribution to carbon neutrality. Numerous research has focused on prototypical experiments employing pure CO2 as a gas source, whereas it remains challenging to understand the intricate impacts of impurity gases on catalysts, hindering the large-scale implementations of flue gas electrolysis. In this study, multiscale simulations and experiments are performed to quantify four types of impurity gas effects, including dilution, competition, electrolyte microenvironment variation, and catalyst performance degradation. Experimental results show that dilution and competition effects impair CO2 electroreduction reaction (CO2RR) performance, and the prepared Ni-based single-atom catalyst exhibits remarkable impurity gas tolerance and maintains a 92 % CO2RR selectivity. Simulation findings suggest that acidic impurity gas boosts CO2 concentration in the electrolyte microenvironment by 27 %, which improves CO2RR selectivity by 18.8 % in experiments. Moreover, elemental sulfur generated from flue gas can physically deposit and chemically dope into the electrode and form sulfur-carbon bonds, causing a U-shaped variation in CO2RR selectivity with the increased SO2 concentration in experiments. A high-speed cyclic scouring method is confirmed to alleviate such performance degradation. The proposed approaches ranging from catalyst design to working processes can promote the industrial application of flue gas electrolysis.