Recent catalytic work has highlighted the importance of grain boundaries in the design of highly active catalyst materials due to the high energy of atoms at strained defect sites. In addition, undercoordinated atoms have long been known to contribute to the catalytic performance of metal nanoparticles. In this work, we describe a method for deliberately increasing the coverage of defect boundaries and undercoordinated atoms at the surfaces of well-defined, symmetric palladium nanoparticles. Careful control of the competitive interactions of chloride and bromide ions with the surface of twinned palladium nanoparticles is used to drive the growth of fin-like structures to extend the area of exposed twin boundaries while also inducing corrugation at the particle surface to add further undercoordinated sites. Mechanistic studies show surface passivation by bromide and etching by chloride in the presence of a low concentration of surfactant to be the key factors that tailor the surface of these nanoparticles, while the internal defect structure is controlled by reaction kinetics. Importantly, these basic principles of competition between surface passivation and etching as well as kinetic control of twin structure are not unique to palladium, and thus this method has the potential to be extended to the enhancement of surface defect density for nanoparticles composed of other catalytically relevant metals.

中文翻译：

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设计缺陷：具有延伸的双缺陷和波纹表面的钯纳米颗粒的合成

最近的催化工作强调了晶界在高活性催化剂材料设计中的重要性，这归因于应变缺陷位点处原子的高能量。另外，人们早就知道配位不足的原子有助于金属纳米颗粒的催化性能。在这项工作中，我们描述了一种方法，用于故意增加明确定义的对称钯纳米粒子表面上的缺陷边界和配位不足的原子的覆盖范围。仔细控制氯离子和溴离子与孪晶钯纳米颗粒表面的竞争性相互作用，可用于驱动鳍状结构的生长，以扩展裸露的孪晶边界的面积，同时还可在颗粒表面引起皱纹，从而进一步增加不协调的位点。机理研究表明，在低浓度的表面活性剂存在下，溴化物的表面钝化和氯化物的蚀刻是定制这些纳米粒子表面的关键因素，而内部缺陷结构则由反应动力学控制。重要的是，这些表面钝化和蚀刻之间竞争的基本原理以及孪晶结构的动力学控制并不是钯所独有的，因此，该方法具有扩展到增强由其他催化相关的纳米颗粒组成的表面缺陷密度的潜力。金属。