Abstract
The electrochemical CO(2) reduction reaction (CO(2)RR) over Pt electrocatalysts in an aqueous solution system yields mainly H(2) and a slight amount of carbon-based products. This limitation can be overcome by using a membrane electrode assembly (MEA) containing a Pt/C electrocatalyst without any overpotential. However, the obtained CO(2)RR product was only CH(4). In this study, we investigated the CO(2)RR using MEA containing a Pt(0.9)Ru(0.1)/C electrocatalyst. Consequently, not only methane as a C(1) product but also ethanol as a C(2) product and acetone as a C(3) product were produced at extremely small overpotentials. This is the first time in the literature that ethanol and acetone were produced from the CO(2)RR over a Pt-Ru-based electrocatalyst. This fact was confirmed through mass spectrometry, gas chromatography, and isotope labeling experiments. The Faradaic efficiencies of CH(4), C(2)H(5)OH, and CH(3)COCH(3) were 20.6%, 5.9%, and 5.2%, respectively, and the total Faradaic efficiency was 31.7%. The three products were generated via the Langmuir-Hinshelwood mechanism involving adsorbed CO (CO(ads)) and H atoms on the electrocatalyst. The adsorption configuration of CO(ads) determines the generation of methane, ethanol, and acetone. The C-C coupling reactions occurred through the formation of CO(ads) clusters. Our findings promote the production of valuable C(2+) compounds from the CO(2)RR, which is an important CO(2) capture, utilization, and storage technology for realizing carbon neutrality.