BioChem - DOS

Efficient and stable acidic CO2 electrolysis to formic acid by a reservoir structure design

Proceedings of the National Academy of Sciences of the United States of America

Chi, Li-Ping; Niu, Zhuang-Zhuang; Zhang, Yu-Cai; Zhang, Xiao-Long; Liao, Jie; Wu, Zhi-Zheng; Yu, Peng-Cheng; Fan, Ming-Hui; Tang, Kai-Bin; Gao, Min-Rui

<P> Electrochemical synthesis of valuable chemicals and feedstocks through carbon dioxide (CO 2 ) reduction in acidic electrolytes can surmount the considerable CO 2 loss in alkaline and neutral conditions. However, achieving high productivity, while operating steadily in acidic electrolytes, remains a big challenge owing to the severe competing hydrogen evolution reaction. Here, we show that vertically grown bismuth nanosheets on a gas-diffusion layer can create numerous cavities as electrolyte reservoirs, which confine in situ-generated hydroxide and potassium ions and limit inward proton diffusion, producing locally alkaline environments. Based on this design, we achieve formic acid Faradaic efficiency of 96.3% and partial current density of 471 mA cm <SUP>&#x2212;2</SUP> at pH 2. When operated in a slim continuous-flow electrolyzer, the system exhibits a full-cell formic acid energy efficiency of 40% and a single pass carbon efficiency of 79% and performs steadily over 50 h. We further demonstrate the production of pure formic acid aqueous solution with a concentration of 4.2 weight %. </P>

2023

Proceedings of the National Academy of Sciences

0027-8424

1091-6490

120

51

pp.e2312876120

10.1073/pnas.2312876120

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