Low-Coordination Sites in Oxygen-Reduction Electrocatalysis: Their Roles and Methods for Removal
Low-Coordination Sites in Oxygen-Reduction Electrocatalysis: Their Roles and Methods for Removal
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DOI：
10.1021/la200753z
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发表时间：
2011-07-05
期刊：
影响因子：
3.9
通讯作者：
Adzic, Radoslav R.
中科院分区：
文献类型：
--
作者：
Cai, Yun;Ma, Chao;Adzic, Radoslav R.
低配位位点，包括边缘、扭结和缺陷，在氧还原电催化中起着重要作用。他们的作用进行了实验研究和理论上的各种Pt表面。然而，类似大小的纳米粒子的粗糙度效应，可以阐明低配位位的作用，吸引了少得多的关注，没有研究的Pd纳米粒子。在这里，使用Br-吸附/脱附，我们介绍了一种有效的方法来降低表面粗糙度，产生Pd纳米粒子具有更光滑的表面和（111）-取向的方面的数量增加。所得纳米颗粒具有轻微收缩的结构和窄的尺寸分布。Pt单层催化剂，含有这样的纳米粒子作为核心表现出1.5倍的比氧还原反应和Pt的质量活动相比，未经处理的增强。此外，用溴化物处理的Pd（3）Co核观察到耐久性的显著增加。这些结果证明了一种简单的方法来制备具有光滑表面的纳米颗粒，并证实了低配位位点对氧还原反应动力学的不利影响。
Low-coordination sites, including edges, kinks, and defects, play an important role in oxygen-reduction electrocatalysis. Their role was studied experimentally and theoretically for various Pt surfaces. However, the roughness effect on similar-sized nanoparticles that could elucidate the role of low-coordination sites has attracted much less attention, with no studies on Pd nanoparticles. Here, using Br- adsorption/desorption, we introduce an effective approach to reduce surface roughness, yielding Pd nanoparticles with smoother surfaces and an increased number of (111)-oriented facets. The resulting nanoparticles have a slightly contracted structure and narrow size distribution. Pt monolayer catalysts that contain such nanoparticles as the cores showed a 1.5-fold enhancement in specific and Pt mass activities for the oxygen reduction reaction compared with untreated ones. Furthermore, a dramatic increase in durability was observed with bromide-treated Pd(3)Co cores. These results demonstrate a simple approach to preparing nanoparticles with smooth surfaces and confirm the adverse effect of low-coordination sites on the kinetics of the oxygen-reduction reaction.