Electrochemistry Laboratory, Paul Scherrer Institut, Forschungsstrasse 111, 5232, Villigen PSI, Switzerland.
Laboratory for Scientific Developments and Novel Materials, Paul Scherrer Institut, Forschungsstrasse 111, 5232, Villigen PSI, Switzerland.
Chemphyschem. 2019 Nov 19;20(22):3120-3127. doi: 10.1002/cphc.201900468. Epub 2019 Jul 31.
The encouraging selectivity of copper oxides for the electroreduction of CO into ethylene and alcohols has led to a vivid debate on the possible relation between their operando (sub-)surface oxidation state (i. e. fully reduced or partially oxidized) and this distinct reactivity. The high roughness of the Cu oxides used in previous studies on this matter adds complexity to this controversy and motivated us to prepare quasi-planar Cu O thin films that displayed a CO reduction selectivity similar to that of oxide-derived copper catalysts reported in previous studies. Most importantly, when the post-mortem thin films were transferred for characterization in an air-free environment, X-ray photoelectron spectroscopy measurements confirmed their complete reduction in the course of the CO reduction reaction. Thus, our results indicate that the selectivity of the Cu oxides featured in previous studies stems from their enhanced roughness, highlighting the importance of controlled sample transfer upon post-mortem characterization with ex situ techniques.
氧化铜对 CO 电化学还原为乙烯和醇的高选择性，引发了关于其操作（亚）表面氧化态（即完全还原或部分氧化）与这种独特反应性之间可能存在关系的激烈争论。在此问题的先前研究中使用的 Cu 氧化物的高粗糙度增加了这一争议的复杂性，并促使我们制备准平面 CuO 薄膜，该薄膜表现出与先前研究中报道的氧化物衍生铜催化剂相似的 CO 还原选择性。最重要的是，当将死后的薄膜转移到无空气环境中进行表征时，X 射线光电子能谱测量证实了它们在 CO 还原反应过程中的完全还原。因此，我们的结果表明，先前研究中 Cu 氧化物的选择性源于其增强的粗糙度，突出了在使用非原位技术进行死后特征描述时对样品进行受控转移的重要性。
