Asymmetrical electrohydrogenation of CO <sub>2</sub> to ethanol with copper–gold heterojunctions
Siyu Kuang, Yaqiong Su, Jianping Li, Hai Liu, Hongyuan Chuai, Xiaoyi Chen, Emiel J. M. Hensen, Thomas J. Meyer, Sheng Zhang, Xinbin Ma
Abstract
Copper is distinctive in electrocatalyzing reduction of CO 2 into various energy-dense forms, but it often suffers from limited product selectivity including ethanol in competition with ethylene. Here, we describe systematically designed, bimetallic electrocatalysts based on copper/gold heterojunctions with a faradaic efficiency toward ethanol of 60% at currents in excess of 500 mA cm −2 . In the modified catalyst, the ratio of ethanol to ethylene is enhanced by a factor of 200 compared to copper catalysts. Analysis by ATR-IR measurements under operating conditions, and by computational simulations, suggests that reduction of CO 2 at the copper/gold heterojunction is dominated by generation of the intermediate OCCOH*. The latter is a key contributor in the overall, asymmetrical electrohydrogenation of CO 2 giving ethanol rather than ethylene.