Electrochemical Carbon Dioxide Reduction in Acidic Media

The electrochemical reduction of carbon dioxide (CO2RR) stands as an enticing approach for the production of essential chemicals and feedstocks, storing clean electric energy and mitigating greenhouse gas emissions. Recent years have witnessed remarkable breakthroughs in CO2RR, enhancing its performance and transitioning related research from laboratory settings toward industrial realization. However, the journey of CO2RR development is not devoid of challenges, including issues like mass transfer limitation, salt accumulation, and flooding phenomena. Remarkably, recent studies have unveiled a promising avenue by conducting CO2RR in an acidic environment, effectively circumventing these challenges and presenting novel opportunities. In this review, we embark on a reassessment of H-cells and flow cells, delving into their opportunities, challenges, strengths, and weaknesses. Additionally, we compile recent advancements in CO2RR under acidic conditions, elucidating the performance metrics and strategies embraced by pertinent research. Subsequently, we propose three pivotal concerns in acidic CO2RR: ① balancing the competition between CO2RR and hydrogen evolution reaction (HER), ② enhancing the selectivity, and ③ exploring industrial applications. And finally, we delve into the core factors influencing the performance of CO2RR in acid: local pH, cation effects, and catalyst design. Building upon these strategies, challenges, and insights, prospects are proposed for the future trajectory of CO2RR development.