Nanoelectrochemistry Laboratory, Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan, Republic of China.
ACS Nano. 2011 Dec 27;5(12):9370-81. doi: 10.1021/nn202545a. Epub 2011 Nov 9.
Although bimetallic core@shell structured nanoparticles (NPs) are achieving prominence due to their multifunctionalities and exceptional catalytic, magnetic, thermal, and optical properties, the rationale underlying their design remains unclear. Here we report a kinetically controlled autocatalytic chemical process, adaptable for use as a general protocol for the fabrication of bimetallic core@shell structured NPs, in which a sacrificial Cu ultrathin layer is autocatalytically deposited on a dimensionally stable noble-metal core under kinetically controlled conditions, which is then displaced to form an active ultrathin metal-layered shell by redox-transmetalation. Unlike thermodynamically controlled under-potential deposition processes, this general strategy allows for the scaling-up of production of high-quality core-shell structured NPs, without the need for any additional reducing agents and/or electrochemical treatments, some examples being Pd@Pt, Pt@Pd, Ir@Pt, and Ir@Pd. Having immediate and obvious commercial potential, Pd@Pt NPs have been systematically characterized by in situ X-ray absorption, electrochemical-FTIR, transmission electron microscopy, and electrochemical techniques, both during synthesis and subsequently during testing in one particularly important catalytic reaction, namely, the oxygen reduction reaction, which is pivotal in fuel cell operation. It was found that the bimetallic Pd@Pt NPs exhibited a significantly enhanced electrocatalytic activity, with respect to this reaction, in comparison with their monometallic counterparts.
虽然双金属核-壳结构纳米粒子（NPs）由于其多功能性和卓越的催化、磁性、热学和光学性能而备受关注，但它们的设计原理仍不清楚。在这里，我们报告了一种动力学控制的自催化化学过程，可作为一种通用的制备双金属核-壳结构 NPs 的方案，其中在动力学控制条件下，牺牲的 Cu 超薄层在尺寸稳定的贵金属核上自催化沉积，然后通过氧化还原转金属置换形成活性超薄金属层壳。与热力学控制的欠电位沉积过程不同，这种通用策略允许高质量核壳结构 NPs 的大规模生产，而无需任何额外的还原剂和/或电化学处理，一些例子是 Pd@Pt、Pt@Pd、Ir@Pt 和 Ir@Pd。Pd@Pt NPs 具有直接而明显的商业潜力，已经通过原位 X 射线吸收、电化学-FTIR、透射电子显微镜和电化学技术进行了系统表征，包括在合成过程中和随后在一个特别重要的催化反应——氧还原反应中的测试，该反应在燃料电池运行中至关重要。结果发现，与单金属对应物相比，双金属 Pd@Pt NPs 在该反应中表现出显著增强的电催化活性。
