氧合物
化学
电催化剂
催化作用
电化学
无机化学
一氧化碳
过电位
铜
电解质
阳极
选择性
电极
有机化学
物理化学
作者
Lei Wang,Stephanie A. Nitopi,Erlend Bertheussen,Marat Orazov,Carlos G. Morales‐Guio,Xinyan Li,Drew Higgins,Karen Chan,Jens K. Nørskov,Christopher Hahn,Thomas F. Jaramillo
标识
DOI:10.1021/acscatal.8b01200
摘要
Understanding the surface reactivity of CO, which is a key intermediate during electrochemical CO2 reduction, is crucial for the development of catalysts that selectively target desired products for the conversion of CO2 to fuels and chemicals. In this study, a custom-designed electrochemical cell is utilized to investigate planar polycrystalline copper as an electrocatalyst for CO reduction under alkaline conditions. Seven major CO reduction products have been observed including various hydrocarbons and oxygenates which are also common CO2 reduction products, strongly indicating that CO is a key reaction intermediate for these further-reduced products. A comparison of CO and CO2 reduction demonstrates that there is a large decrease in the overpotential for C–C coupled products under CO reduction conditions. The effects of CO partial pressure and electrolyte pH are investigated; we conclude that the aforementioned large potential shift is primarily a pH effect. Thus, alkaline conditions can be used to increase the energy efficiency of CO and CO2 reduction to C–C coupled products, when these cathode reactions are coupled to the oxygen evolution reaction at the anode. Further analysis of the reaction products reveals common trends in selectivity that indicate both the production of oxygenates and C–C coupled products are favored at lower overpotentials. These selectivity trends are generalized by comparing the results on planar Cu to current state-of-the-art high-surface-area Cu catalysts, which are able to achieve high oxygenate selectivity by operating at the same geometric current density at lower overpotentials. Combined, these findings outline key principles for designing CO and CO2 electrolyzers that are able to produce valuable C–C coupled products with high energy efficiency.
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