Asymmetrical electrohydrogenation of CO<sub>2</sub> to ethanol with copper-gold heterojunctions.

Kuang, Siyu; Su, Yaqiong; Li, Minglu; Liu, Hai; Chuai, Hongyuan; Chen, Xiaoyi; Hensen, Emiel J M; Meyer, Thomas J et al. · Proc Natl Acad Sci U S A · 2023

basic_science · Level V

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Abstract

Copper is distinctive in electrocatalyzing reduction of CO<sub>2</sub> 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<sup>-2</sup>. 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<sub>2</sub> 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<sub>2</sub> giving ethanol rather than ethylene.