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Sequential catalysis controls selectivity in electrochemical CO2 reduction on Cu†
Energy & Environmental Science ( IF 32.5 ) Pub Date : 2018-07-06 00:00:00 , DOI: 10.1039/c8ee01501e
Yanwei Lum 1, 2, 3, 4, 5 , Joel W. Ager 1, 2, 3, 4, 5
Affiliation  

Electrochemical reduction of CO2 in aqueous media is a strategy for sustainable production of fuels and commodity chemicals. Cu is the only catalyst which converts CO2 to significant quantities of hydrocarbons and oxygenates. Here we demonstrate that oxygenate products can be favored over hydrocarbons by positioning a local source of CO generated by a CO producing catalyst (Au or Ag) in close proximity to a Cu catalyst. Use of a bimetallic device comprising interdigitated and independently controllable lines of Au and Cu allows the local CO concentration to be modulated. Notably, diffusional simulations show that the saturation concentration of CO can be exceeded locally. Actuating both the Au and Cu lines increases the oxygenate to ethylene ratio compared to actuating Cu only. Increasing the relative area of CO-producing Au relative to Cu also increases this ratio. These insights are translated into a second bimetallic system comprising Cu dots/lines patterned directly onto a Ag substrate, allowing for the distance between Cu and the CO generating metal to be precisely controlled. Controlling the relative areas of Ag and Cu allows for tuning of the oxygenate to ethylene ratio from 0.59 to 2.39 and an increase in oxygenate faradaic efficiency from 21.4% to 41.4%, while maintaining the selectivity to C2/C3 products in the 50–65% range. We attribute this change in selectivity to be due to an increased *CO coverage on Cu. By utilizing diffusional transport of CO to the Cu, a sequential catalysis pathway is created which allows for the control of oxygenate selectivity in aqueous CO2 reduction.

中文翻译:

顺序催化控制在Cu 上电化学还原CO 2的选择性

电化学还原水性介质中的CO 2是可持续生产燃料和日用化学品的策略。铜是唯一可转化CO 2的催化剂大量的碳氢化合物和含氧化合物。在这里,我们证明,通过将由产CO的催化剂(Au或Ag)生成的局部CO来源与Cu催化剂紧密相连,可以使含氧化合物的产品优于烃类。使用包括相互交叉且可独立控制的Au和Cu线的双金属器件,可以调节局部CO浓度。值得注意的是,扩散模拟表明可以局部超过CO的饱和浓度。与仅致动Cu相比,致动Au和Cu线均增加了含氧化合物与乙烯的比率。增加产生CO的Au相对于Cu的相对面积也增加了该比率。这些见解转化为第二个双金属系统,包括直接在Ag衬底上构图的Cu点/线,可以精确控制Cu和生成CO的金属之间的距离。控制Ag和Cu的相对面积可将含氧化合物与乙烯的比例从0.59调整至2.39,并将含氧化合物的法拉第效率从21.4%提高至41.4%,同时保持对C的选择性2 / C 3产品在50–65%的范围内。我们将这种选择性的变化归因于Cu上* CO覆盖率的提高。通过利用CO到Cu的扩散传输,创建了一个顺序催化路径,该路径可以控制含水CO 2还原中含氧化合物的选择性。
更新日期:2018-07-06
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