School of Chemical Engineering, The University of Queensland, St Lucia, 4072, Australia.
Center for Future Materials, University of Southern Queensland, Springfield, 4300, Australia.
ChemSusChem. 2020 Jan 19;13(2):304-311. doi: 10.1002/cssc.201902433. Epub 2019 Nov 6.
Achieving high product selectivities is one challenge that limits viability of electrochemical CO reduction (CO R) to chemical feedstocks. Here, it was demonstrated how interactions between Ag foil cathodes and reline (choline chloride + urea) led to highly selective CO R to CO with a faradaic efficiency of (96±8) % in 50 wt % aqueous reline at -0.884 V vs. the reversible hydrogen electrode (RHE), which is a 1.5-fold improvement over CO R in KHCO . In reline the Ag foil was roughened by (i) dissolution of oxide layers followed by (ii) electrodeposition of Ag nanoparticles back on cathode. This surface restructuring exposed low-coordinated Ag atoms, and subsequent adsorption of choline ions and urea at the catalyst surface limited proton availability in the double layer and stabilized key intermediates such as *COOH. These approaches could potentially be extended to other electrocatalytic metals and lower-viscosity deep eutectic solvents to achieve higher-current-density CO R in continuous-flow cell electrolyzers.
实现高产物选择性是限制电化学 CO 还原（CO R）应用于化学原料的一个挑战。在这里，研究了银箔阴极与电解液（氯化胆碱+尿素）之间的相互作用如何导致高选择性 CO R 生成 CO，在 -0.884 V 相对于可逆氢电极（RHE）的条件下，在 50wt%水基电解液中的法拉第效率为（96±8）%，这比在 KHCO 中进行 CO R 的效率提高了 1.5 倍。在电解液中，银箔通过（i）氧化层的溶解，然后（ii）在阴极上重新电沉积 Ag 纳米颗粒，从而变得粗糙。这种表面重构暴露了低配位的 Ag 原子，随后在催化剂表面吸附胆碱离子和尿素，限制了双层中的质子可用性，并稳定了关键中间体，如*COOH。这些方法可能会扩展到其他电催化金属和低粘度深共晶溶剂，以在连续流动电池电解槽中实现更高电流密度的 CO R。
