Electrifying HCOOH synthesis from CO <sub>2</sub> building blocks over Cu–Bi nanorod arrays
Guiru Zhang, Bing Tan, Dong Hyeon Mok, Huiya Liu, Baoxin Ni, Gui Zhao, Ke Ye, Shengjuan Huo, Xiaohe Miao, Zheng Liang, Xi Liu, Liwei Chen, Zemin Zhang, Wen‐Bin Cai, Seoin Back, Kun Jiang
Abstract
Precise electrochemical synthesis of commodity chemicals and fuels from CO 2 building blocks provides a promising route to close the anthropogenic carbon cycle, in which renewable but intermittent electricity could be stored within the greenhouse gas molecules. Here, we report state-of-the-art CO 2 -to-HCOOH valorization performance over a multiscale optimized Cu–Bi cathodic architecture, delivering a formate Faradaic efficiency exceeding 95% within an aqueous electrolyzer, a C-basis HCOOH purity above 99.8% within a solid-state electrolyzer operated at 100 mA cm −2 for 200 h and an energy efficiency of 39.2%, as well as a tunable aqueous HCOOH concentration ranging from 2.7 to 92.1 wt%. Via a combined two-dimensional reaction phase diagram and finite element analysis, we highlight the role of local geometries of Cu and Bi in branching the adsorption strength for key intermediates like *COOH and *OCHO for CO 2 reduction, while the crystal orbital Hamiltonian population analysis rationalizes the vital contribution from moderate binding strength of η 2 (O,O)-OCHO on Cu-doped Bi surface in promoting HCOOH electrosynthesis. The findings of this study not only shed light on the tuning knobs for precise CO 2 valorization, but also provide a different research paradigm for advancing the activity and selectivity optimization in a broad range of electrosynthetic systems.