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.