Department of Chemistry, State University of New York at Binghamton, Binghamton, NY 13902, USA.
Nanotechnology. 2010 Feb 10;21(6):062001. doi: 10.1088/0957-4484/21/6/062001. Epub 2010 Jan 12.
One of the most important challenges for the ultimate commercialization of fuel cells is the preparation of active, robust, and low-cost catalysts. This review highlights some findings of our investigations in the last few years in developing advanced approaches to nanostructured catalysts that address this challenge. Emphasis is placed on nanoengineering-based fabrication, processing, and characterization of multimetallic nanoparticles with controllable size (1-10 nm), shape, composition (e.g. Ml(n)M2(100-n), M1(n)M2(m)M3(100-n-m), M1@M2, where M (1 or 2) = Pt, Co, Ni, V, Fe, Cu, Pd, W, Ag, Au etc) and morphology (e.g. alloy, core@shell etc). In addition to an overview of the fundamental issues and the recent progress in fuel cell catalysts, results from evaluations of the electrocatalytic performance of nanoengineered catalysts in fuel cell reactions are discussed. This approach differs from other traditional approaches to the preparation of supported catalysts in the ability to control the particle size, composition, phase, and surface properties. An understanding of how the nanoscale properties of the multimetallic nanoparticles differ from their bulk-scale counterparts, and how the interaction between the nanoparticles and the support materials relates to the size sintering or evolution in the thermal activation process, is also discussed. The fact that the bimetallic gold-platinum nanoparticle system displays a single-phase character different from the miscibility gap known for its bulk-scale counterpart serves as an important indication of the nanoscale manipulation of the structural properties, which is useful for refining the design and preparation of the bimetallic catalysts. The insight gained from probing how nanoparticle-nanoparticle and nanoparticle-substrate interactions relate to the size evolution in the activation process of nanoparticles on planar substrates serves as an important guiding principle in the control of nanoparticle sintering on different support materials. The fact that some of the trimetallic nanoparticle catalysts (e.g. PtVFe or PtNiFe) exhibit electrocatalytic activities in fuel cell reactions which are four-five times higher than in pure Pt catalysts constitutes the basis for further exploration of a variety of multimetallic combinations. The fundamental insights into the control of nanoscale alloy, composition, and core-shell structures have important implications in identifying nanostructured fuel cell catalysts with an optimized balance of catalytic activity and stability.
对于燃料电池的最终商业化而言，最重要的挑战之一是制备活性高、稳定性强且成本低的催化剂。本文重点介绍了我们在过去几年中针对纳米结构催化剂的一些研究成果，这些研究成果为解决这一挑战提供了先进的方法。重点介绍了基于纳米工程的制造、加工和多金属纳米粒子的可控尺寸（1-10nm）、形状、组成（例如 Ml(n)M2(100-n)、M1(n)M2(m)M3(100-n-m)、M1@M2，其中 M（1 或 2）=Pt、Co、Ni、V、Fe、Cu、Pd、W、Ag、Au 等）和形态（例如合金、核壳等）的纳米结构催化剂的制备。除了对燃料电池催化剂的基本问题和最新进展进行概述外，还讨论了纳米工程催化剂在燃料电池反应中电催化性能评估的结果。与传统的负载型催化剂制备方法相比，这种方法能够控制颗粒尺寸、组成、相和表面特性。讨论了如何理解多金属纳米粒子的纳米尺度特性与其体相尺度特性的不同，以及纳米粒子与支撑材料之间的相互作用如何与热激活过程中的颗粒烧结或演变相关。双金属金-铂纳米粒子系统显示出不同于其体相尺度对应物的已知混溶性间隙的单相特性，这一事实表明，对结构特性的纳米尺度操控有助于改进双金属催化剂的设计和制备。从探测纳米粒子-纳米粒子和纳米粒子-基底相互作用如何与纳米粒子在基底上的激活过程中的尺寸演变相关中获得的见解，为控制不同支撑材料上的纳米粒子烧结提供了重要的指导原则。一些三金属纳米粒子催化剂（例如 PtVFe 或 PtNiFe）在燃料电池反应中的电催化活性比纯 Pt 催化剂高 4-5 倍，这一事实为进一步探索各种多金属组合奠定了基础。对纳米尺度合金、组成和核壳结构的控制的深入了解，对于识别具有优化的催化活性和稳定性平衡的纳米结构燃料电池催化剂具有重要意义。
