Department of Chemistry, Stanford University, 337 Campus Drive, Stanford, CA 94305, USA.
Department of Chemistry, University of Utah, 315 S 1400 E, Salt Lake City, UT 84112, USA.
Science. 2017 Dec 1;358(6367):1187-1192. doi: 10.1126/science.aao3691.
Altering a material's catalytic properties requires identifying structural features that give rise to active surfaces. Grain boundaries create strained regions in polycrystalline materials by stabilizing dislocations and may provide a way to create high-energy surfaces for catalysis that are kinetically trapped. Although grain-boundary density has previously been correlated with catalytic activity for some reactions, direct evidence that grain boundaries create surfaces with enhanced activity is lacking. We used a combination of bulk electrochemical measurements and scanning electrochemical cell microscopy with submicrometer resolution to show that grain-boundary surface terminations in gold electrodes are more active than grain surfaces for electrochemical carbon dioxide (CO) reduction to carbon monoxide (CO) but not for the competing hydrogen (H) evolution reaction. The catalytic footprint of the grain boundary is commensurate with its dislocation-induced strain field, providing a strategy for broader exploitation of grain-boundary effects in heterogeneous catalysis.
改变材料的催化性能需要确定产生活性表面的结构特征。晶界通过稳定位错在多晶材料中产生应变区，并可能为催化提供一种创建动力学捕获的高能表面的方法。尽管晶界密度与某些反应的催化活性之前已经相关，但缺乏晶界创建具有增强活性表面的直接证据。我们使用体电化学测量和具有亚微米分辨率的扫描电化学池显微镜的组合，表明金电极中的晶界表面终止比晶界表面更活跃，用于电化学二氧化碳（CO）还原为一氧化碳（CO），但对于竞争的氢（H）演化反应则不然。晶界的催化足迹与位错诱导的应变场相称，为更广泛地利用多相催化中的晶界效应提供了一种策略。
