Stable, active CO2 reduction to formate via redox-modulated stabilization of active sites
Le Li, Adnan Ozden, Shuyi Guo, F. Pelayo Garcı́a de Arquer, Chuanhao Wang, Mingzhe Zhang, Jin Zhang, Haoyang Jiang, Wei Wang, Hao Dong, David Sinton, Edward H. Sargent, Miao Zhong
Abstract
Abstract Electrochemical reduction of CO 2 (CO 2 R) to formic acid upgrades waste CO 2 ; however, up to now, chemical and structural changes to the electrocatalyst have often led to the deterioration of performance over time. Here, we find that alloying p-block elements with differing electronegativities modulates the redox potential of active sites and stabilizes them throughout extended CO 2 R operation. Active Sn-Bi/SnO 2 surfaces formed in situ on homogeneously alloyed Bi 0.1 Sn crystals stabilize the CO 2 R-to-formate pathway over 2400 h (100 days) of continuous operation at a current density of 100 mA cm −2 . This performance is accompanied by a Faradaic efficiency of 95% and an overpotential of ~ −0.65 V. Operating experimental studies as well as computational investigations show that the stabilized active sites offer near-optimal binding energy to the key formate intermediate *OCHO. Using a cation-exchange membrane electrode assembly device, we demonstrate the stable production of concentrated HCOO – solution (3.4 molar, 15 wt%) over 100 h.