Copper oxides have recently emerged as promising precursor catalyst materials demonstrating enhanced reactivity and selectivity towards C2 and C3 products like ethylene, ethanol, and n-propanol generated from the direct electro-reduction reaction of CO₂ (denoted as CO₂RR). Advanced operando X-ray absorption spectroscopy (XAS), X-ray diffraction (XRD) and Raman spectroscopy were employed to probe the potential-dependent changes of the chemical states of Cu species in the Cu oxide foams (referred to as Cu_xO) before and during the CO₂RR. This complementary and holistic approach of ‘bulk’- and surface-sensitive techniques demonstrates that the electro-reduction of Cu_xO foams into metallic Cu is completed before hydrocarbon (e.g., ethylene, ethane) and alcohol (e.g., ethanol, n-propanol) formation sets in. There are, however, substantial differences in the potential dependence of the oxide reduction when comparing the ‘bulk’ with the respective ‘surface’ processes. Only in the very initial stage of the CO₂RR, the reduction of the Cu oxide precursor species is temporarily superimposed on the production of CO and H₂. Complementary identical location (IL) SEM analysis of the Cu_xO foams prior to and after the CO₂RR reveals a significant alteration in the surface morphology caused by the appearance of smaller Cu nanoparticles formed by the reduction process of Cu_xO species.

氧化铜最近已经成为有希望的前体催化剂材料，其显示出对由CO ₂（直接表示为CO ₂ RR）直接电还原反应生成的C2和C3产品（如乙烯，乙醇和正丙醇）的反应性和选择性增强。使用先进的操作X射线吸收光谱（XAS），X射线衍射（XRD）和拉曼光谱来探测氧化铜泡沫中Cu物种的化学状态的电势依赖性变化（称为Cu _x O）在CO ₂ RR之前和期间。“批量”和表面敏感技术的这种互补而整体的方法表明，Cu _x的电还原在形成碳氢化合物（例如，乙烯，乙烷）和醇（例如，乙醇，正丙醇）之前，O泡沫已经完成形成金属Cu。但是，当比较“批量”和相应的“表面”处理。仅在CO ₂ RR的最开始阶段，Cu氧化物前体物质的还原会暂时叠加在CO和H _{2的产生上}。在CO ₂ RR之前和之后，对Cu _x O泡沫的互补相同位置（IL）SEM分析显示，由于由Cu _x O物种的还原过程形成的较小的Cu纳米颗粒的出现，导致了表面形态的重大变化。