PtSn Intermetallic, Core-Shell, and Alloy Nanoparticles as CO-Tolerant Electrocatalysts for H2 Oxidation
PtSn Intermetallic, Core-Shell, and Alloy Nanoparticles as CO-Tolerant Electrocatalysts for H2 Oxidation
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DOI：
10.1002/anie.200907019
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发表时间：
2010-01-01
影响因子：
16.6
通讯作者：
Eichhorn, Bryan W.
中科院分区：
文献类型：
--
作者：
Liu, Zhufang;Jackson, Greg S.;Eichhorn, Bryan W.
一氧化碳（CO）是重整碳氢化合物衍生的H2燃料中的主要杂质，其对Pt电催化剂的毒害限制了基于Nafion的质子交换膜（PEM）燃料电池的商业化。[1]为了减轻PEM燃料电池中的CO中毒效应，一种直接的策略是用可以耐受少量CO（通常< 100 ppm）的Pt基双金属电催化剂代替Pt。为此目的，已经研究了三种有前途的基于Pt的纳米颗粒：1）金属原子随机分布在面心立方（fcc）晶格中的Pt-M合金（例如PtRu），[2-4] 2）具有明确组成和晶体结构的有序金属间化合物（例如PtBi），[5]和3）核-壳双金属化合物，例如Ru-核/Pt壳（Ru@ Pt），其中Pt集中在Ru纳米颗粒表面上。[6]每一个这样的体系结构在电催化应用中的合成可及性、性能和稳定性方面都有潜在的优点和缺点。然而，这三个架构在一个特定的Pt-M series的直接比较还没有reported.We描述在这里的合成，表征，电催化性能，和稳定性的PtSn合金，核壳，金属间纳米粒子（NP）的组成和大小相同。这些研究表明，PtSn金属间化合物在酸性电解质溶液中相对于PtSn合金显著更稳定并且具有上级性能。此外，金属间化合物可以通过在CO饱和的H2SO 4溶液中的连续电位循环过程转化为PtSn@ Pt核-壳颗粒，而PtSn无规合金没有形成这样的核-壳结构。PtSn@ Pt和PtSn金属间NP电催化剂显示出比商业E-TEK PtRu和Pt催化剂显著更好的CO耐受性，但推测涉及不同的CO氧化机理。
The poisoning of Pt electrocatalysts by carbon monoxide (CO), a major impurity in H2 fuels derived from reformed hydrocarbons, limits the commercialization of Nafion-based proton-exchange membrane (PEM) fuel cells.[1] To mitigate the CO-poisoning effect in PEM fuel cells, one straightforward strategy is to replace Pt with Pt-based bimetallic electrocatalysts that can tolerate small amounts of CO (typically< 100 ppm). Three promising classes of Pt-based bimetallic NPs have been investigated for this purpose: 1) Pt–M alloys (eg PtRu) with metal atoms randomly distributed in face-centered-cubic (fcc) lattices,[2–4] 2) ordered intermetallics (eg PtBi) that have well-defined compositions and crystal structures,[5] and 3) core–shell bimetallics, eg Ru-core/Ptshell (Ru@ Pt) in which Pt is concentrated on the Ru nanoparticle surface.[6] Each of these bimetallic architectures has potential advantages and disadvantages in terms of synthetic accessibility, performance, and stability in electrocatalytic applications. However, a direct comparison of these three architectures in a specific Pt–M series has not been reported.We describe here the synthesis, characterization, electrocatalytic performance, and stabilities of PtSn alloy, core–shell, and intermetallic nanoparticles (NPs) of the same composition and size. These studies show that the PtSn intermetallic is significantly more stable and has superior performance relative to the PtSn alloy in acidic electrolyte solutions. In addition, the intermetallic can be converted to a PtSn@ Pt core–shell particle through a successive potential cycling process in CO-saturated H2SO4 solutions, while no such core–shell structure forms from PtSn random alloys. The PtSn@ Pt and PtSn intermetallic NP electrocatalysts show significantly better CO-tolerance than commercial E-TEK PtRu and Pt catalysts but presumably involve different CO oxidation mechanisms.