Nano-folded Gold Catalysts for Electroreduction of Carbon Dioxide
Nano-folded Gold Catalysts for Electroreduction of Carbon Dioxide
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DOI：
10.1021/acs.nanolett.9b04564
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发表时间：
2019-12-01
期刊：
影响因子：
10.8
通讯作者：
Gracias, David H.
中科院分区：
文献类型：
--
作者：
Kwok, Kam Sang;Wang, Yuxuan;Gracias, David H.
催化界面的局部结构和几何形状会影响化学反应的选择性。选择性对于二氧化碳 (CO2) 电还原等反应的实际实现至关重要。先前开发的控制 CO2 电还原催化剂的结构和几何形状的策略涉及复杂的过程或无法有效地改变选择性。在这里，我们使用预应变聚合物，单轴和双轴压缩 60 nm 金膜，形成用于 CO2 还原的纳米折叠电催化剂。我们观察了两种折叠，并且可以通过改变聚合物中的预应变程度来调整松散与紧密折叠的比率。我们使用 X 射线衍射、扫描和透射电子显微镜表征纳米折叠催化剂。我们观察到纳米折叠金催化剂中的晶粒重新取向和粗化。我们测量到，与扁平催化剂相比，双轴压缩纳米折叠催化剂形成一氧化碳的法拉第效率提高了约九倍（高达 87.4%）。我们通过注意到催化剂紧密褶皱中局部 pH 值的增加超过了颗粒特性改变的影响来合理化这一观察结果。总之，我们的研究表明，纳米折叠几何形状可以显着改变颗粒特性、传质和催化性能。
The local structure and geometry of catalytic interfaces can influence the selectivity of chemical reactions. Selectivity is often critical for the practical realization of reactions such as the electroreduction of carbon dioxide (CO2). Previously developed strategies to manipulate the structure and geometry of catalysts for electroreduction of CO2 involve complex processes or fail to efficiently alter the selectivity. Here, using a prestrained polymer, we uniaxially and biaxially compress a 60 nm gold film to form a nano-folded electrocatalyst for CO2 reduction. We observe two kinds of folds and can tune the ratio of loose to tight folds by varying the extent of prestrain in the polymer. We characterize the nano-folded catalysts using X-ray diffraction, scanning, and transmission electron microscopy. We observe grain reorientation and coarsening in the nano-folded gold catalysts. We measure an enhancement of Faradaic efficiency for carbon monoxide formation with the biaxially compressed nano-folded catalyst by a factor of about nine as compared to the flat catalyst (up to 87.4%). We rationalize this observation by noting that an increase of the local pH in the tight folds of the catalyst outweighs the effects of alterations in grain characteristics. Together, our studies demonstrate that nano-folded geometries can significantly alter grain characteristics, mass transport, and catalytic performance.