Durable CO2 conversion in the proton-exchange membrane system

• Published in: Nature (London) 2024-02, Vol.626 (7997), p.86-91
• Main Authors: Fang, Wensheng, Guo, Wei, Lu, Ruihu, Yan, Ya, Liu, Xiaokang, Wu, Dan, Li, Fu Min, Zhou, Yansong, He, Chaohui, Xia, Chenfeng, Niu, Huiting, Wang, Sicong, Liu, Youwen, Mao, Yu, Zhang, Chengyi, You, Bo, Pang, Yuanjie, Duan, Lele, Yang, Xuan, Song, Fei, Zhai, Tianyou, Wang, Guoxiong, Guo, Xingpeng, Tan, Bien, Yao, Tao, Wang, Ziyun, Xia, Bao Yu
• Format: Article
• Language: English
• Subjects: 140/133; 639/301/299; 639/4077/4057; 639/638/224/685; 639/638/77; 706/4066/4067; Acids; Carbon dioxide; Carbonates; Catalysts; Efficiency; Electrodes; Electrolysis; Electrolytes; Electron microscopes; Formic acid; Fourier transforms; Humanities and Social Sciences; Hydrogen; Lead acid batteries; Membranes; Microscopy; multidisciplinary; Oxidation; Precipitates; Protons; Robustness; Science; Science (multidisciplinary); Spectrum analysis; Working conditions
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-023-06917-5

Electrolysis that reduces carbon dioxide (CO 2 ) to useful chemicals can, in principle, contribute to a more sustainable and carbon-neutral future 1 – 6 . However, it remains challenging to develop this into a robust process because efficient conversion typically requires alkaline conditions in which CO 2 precipitates as carbonate, and this limits carbon utilization and the stability of the system 7 – 12 . Strategies such as physical washing, pulsed operation and the use of dipolar membranes can partially alleviate these problems but do not fully resolve them 11 , 13 – 15 . CO 2 electrolysis in acid electrolyte, where carbonate does not form, has therefore been explored as an ultimately more workable solution 16 – 18 . Herein we develop a proton-exchange membrane system that reduces CO 2 to formic acid at a catalyst that is derived from waste lead–acid batteries and in which a lattice carbon activation mechanism contributes. When coupling CO 2 reduction with hydrogen oxidation, formic acid is produced with over 93% Faradaic efficiency. The system is compatible with start-up/shut-down processes, achieves nearly 91% single-pass conversion efficiency for CO 2 at a current density of 600 mA cm −2 and cell voltage of 2.2 V and is shown to operate continuously for more than 5,200 h. We expect that this exceptional performance, enabled by the use of a robust and efficient catalyst, stable three-phase interface and durable membrane, will help advance the development of carbon-neutral technologies. We develop a proton-exchange membrane system that reduces CO 2 to formic acid at a catalyst that is derived from waste lead–acid batteries and in which a lattice carbon activation mechanism contributes.