富氧空位的非晶氧化铜高选择性电催化还原CO2制乙烯（英文）

过量化石能源的消耗导致大气中的二氧化碳含量不断上升,由此引发包括温室效应在内的环境问题。对此,常温常压下的电催化二氧化碳还原手段为制备高附加值的化工原料和实现碳循环提供了一种很有前景的技术储备。在众多的二氧化碳还原产物中,碳氢化合物尤其是乙烯,它作为塑料和其他化工产品的重要原料受到广泛的关注。电催化二氧化碳还原制乙烯工艺不仅可适配于现有的生产设备也可作为取代目前工业化的裂解方法。近年来,研究者们为了开发高效的电催化二氧化碳还原制乙烯催化剂开展了大量的研究。不过值得注意的是,大部分研究集中于铜基材料。尽管目前研究者取得了很多成果,但仍缺少可高选择性产乙烯的二氧化碳还原催化剂。如何设计出可活化二氧化碳分子,同时对*CO和*COH中间物有强吸附能力的催化剂是研究难点。针对此问题,本文中通过真空蒸镀的方法制备出一种富氧空位的非晶氧化铜纳米薄膜催化剂。受益于纳米薄膜的构建和氧空位的引入,该催化剂可快速进行电荷和物质的交换,并利于二氧化碳分子的吸附及优化还原中间产物的亲和力,进而表现出优异的电催化二氧化碳制乙烯的性能。结果表明,在加有0.1 mol·L^-1碳酸氢钾溶液的H型电...

Oxygen Vacancy-Rich Amorphous Copper Oxide Enables Highly Selective Electroreduction of Carbon Dioxide to Ethylene

The ever-increasing carbon dioxide (CO₂) emissions caused by excessive fossil fuel consumption induce environmental issues such as global warming. To overcome this, the electrocatalytic CO₂ reduction (ECR) under ambient conditions offers an appealing approach for converting CO₂ to value-added chemicals and realizing a closed carbon loop. Among the ECR products, ethylene (C₂H₄), an important building block for plastics and other chemicals, has attracted considerable attention owing to its compatibility with existing infrastructure and the promising substitution of industrial steam cracking. In recent years, numerous efforts have been devoted to developing highly active and selective catalysts for converting CO₂ to C₂H₄, with most studies having focused on Cu-based materials. Despite the significant advancements made to date, the development of the ECR-to-C₂H₄ process is still hindered by the lack of suitable catalysts that can effectively activate CO₂ and strengthen the surface binding of *CO and *COH species. In this study, an amorphous copper oxide (CuO_x) nanofilm that is rich in oxygen vacancies was prepared via a facile vacuum evaporation method for the efficient electrocatalytic conversion of CO₂ to C₂H₄. It was expected that the nano-scale electrode thickness would greatly accelerate charge- and mass-transfer during CO₂ electrolysis. Moreover, the introduction of oxygen vacancies favored the adsorption of CO₂ and intermediates. As a result, in a typical H-cell, the synthesized defective catalyst delivered a maximum Faradaic efficiency of 85 ± 3% at ?1.3 V versus the reversible hydrogen electrode and maintained a stable C₂H₄ selectivity over 48 h in a 0.1 M potassium bicarbonate solution. Interestingly, the performance observed with the synthesized electrocatalyst in this study is comparable with that of state-of-the-art Cu-based ECR catalysts. Additional structural and chemical characterizations confirmed the robust nature of the as-prepared catalyst. Moreover, when the catalyst was utilized in a membrane electrode assembly cell, it achieved a maximum C₂H₄ partial current density of approximately 115.4 mA?cm^?2 at a cell voltage of ?1.95 V and Faradaic efficiency of 78 ± 2% at a cell voltage of ?1.75 V. Furthermore, theoretical and experimental analyses revealed that oxygen defects not only favored CO₂ adsorption but also enabled strong affinities for *CO and *COH intermediates, which synergistically contributed to a high selectivity for C₂H₄ formation. We believe that our present work will motivate the exploration of amorphous Cu-based materials for achieving efficient CO₂-to-C₂H₄ electrolysis and be a guide towards fundamentally understanding the mechanism of catalytic CO₂ reduction.