Effects of Ag Nanoparticle Coated Metal Electrodes on Electrochemical CO2 Reduction in Aqueous KHCO3 (Supporting Information)

Electrochemical CO2 reduction is crucial for developing a sustainable closed-carbon-cycle society; however, the factors determining product selectivity have not been fully established, especially when the reaction is carried out over metal cathodes. The selectivity of the CO2 reduction pathway can be improved by modifying the cathode’s catalyst surface. This can be achieved by using specific surface of single crystal or by alloying through the addition of an impurity. In this study, the products of electrochemical CO2 reduction were evaluated in an aqueous KHCO3 system at various applied currents and with various metal cathodes. The metal cathodes were coated by Ag nanoparticles, as the Ag cathode was determined to yield the best Faradaic efficiency for CO production in an aqueous KHCO3 system. Our results suggest that some Ag coated cathodes enhance CO2 reduction, and thus the reduction products are tunable through surface modification.电化学二氧化碳还原（Electrochemical CO2 reduction）对于构建可持续闭合碳循环社会至关重要；然而，决定产物选择性的核心机制尚未完全阐明，尤其是在以金属作为阴极的反应体系中。可通过调控阴极催化剂表面来优化二氧化碳还原反应路径的产物选择性，具体手段包括采用特定晶面的单晶催化剂，或是通过掺杂杂质实现合金化改性。本研究在碳酸氢钾（KHCO3）水溶液体系中，针对不同施加电流与不同金属阴极，开展了电化学二氧化碳还原产物的评测实验。本研究中所用的金属阴极均包覆有银纳米颗粒，这是因为在碳酸氢钾水溶液体系中，银阴极被证实可实现一氧化碳（CO）生成的最优法拉第效率（Faradaic efficiency）。研究结果表明，部分包覆银纳米颗粒的阴极可强化二氧化碳还原反应，因此可通过表面改性调控还原产物的分布。