Interfacial Electronic Structures and the Fischer–Tropsch Synthesis Path by Electrochemical CO<sub>2</sub>/CO Reduction for Ternary CuNiZn Alloys
Go Eun Park, Hye Ji Jang, Ju Young Maeng, Seon Young Hwang, Seo Young Yang, Choong Kyun Rhee, Youngku Sohn
Abstract
Metal alloy electrocatalysts are commonly used in electrochemical (EC) CO 2 reduction. In this study, we demonstrate the application of a ternary CuNiZn alloy as an electrocatalyst for both CO 2 and CO reductions. Our results show that formate, CO, CH 4, and C 2–7 hydrocarbons were produced through the process of initial CO 2 adsorption followed by subsequent stepwise reactions. Interestingly, we also observed the production of CH 4 and C 2–7 hydrocarbons (C n H 2 n +2 and C n H 2 n ) through EC CO reduction, which occurred via direct CO adsorption, followed by hydrogenation reactions. Furthermore, we discovered an electrochemically-induced surface reaction that mimics the Fischer–Tropsch (F–T) synthesis, resulting in the formation of long-chain hydrocarbons through C–C coupling/polymerization. We utilized X-ray photoelectron spectroscopy with Ar + ion sputtering depth to investigate the interfacial electronic structures and surface elemental composition distributions of Cu, Ni, and Zn. Our results indicate that these properties are highly dependent on both the applied potential and the depth at which they are measured. These unique observation provides significant insights into the EC F–T synthesis process, C–C coupling mechanism, the design of efficient metal alloy electrodes, and the theoretical modeling of alloys in both electrochemical CO 2 reduction and CO reduction.