Electrochemical and Structural Study of a Chemically Dealloyed PtCu Oxygen Reduction Catalyst.
Electrochemical and Structural Study of a Chemically Dealloyed PtCu Oxygen Reduction Catalyst.
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DOI：
10.1021/jp106042z
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发表时间：
2010-10-07
影响因子：
3.7
通讯作者：
Irish, Nicholas P.
中科院分区：
文献类型：
--
作者：
Dutta, Indrajit;Carpenter, Michael K.;Balogh, Michael P.;Ziegelbauer, Joseph M.;Moylan, Thomas E.;Atwan, Mohammed H.;Irish, Nicholas P.
采用多步合成法制备了一种碳负载、非合金化的铂铜氧还原催化剂。用高角环状暗场扫描电子显微镜(HAADF-STEM)、电子能量损失谱(EELS)、X射线吸收光谱(XAS)、X射线衍射仪(X射线衍射仪)和循环伏安法(CV)对每一步制备的材料进行了表征，并用薄膜转盘电极(TF-RDE)技术测量了其氧还原反应(ORR)活性。最初的合成步骤是金属盐的共还原，产生了一系列结晶不佳的铂、铜和铂-铜合金纳米颗粒，但仍具有良好的ORR活性。这种材料的退火使金属合金化，并增加了颗粒尺寸和结晶度。透射电子显微镜显示，退火后的催化剂包括不同尺寸的颗粒，大颗粒(>；25 nm)、中等颗粒(12-25 nm)和小颗粒(<；12 nm)。大多数中小颗粒表现出部分或完全的核壳结构(富铜核和铂壳)，较小的颗粒通常具有更完整的壳层。退火后出现的铂壳表明，它们是由热扩散机制形成的。尽管催化剂材料的比活性在热处理后增加了一倍以上，但随之而来的铂比表面积的减少导致了其质量活性的下降。随后通过酸处理催化剂的脱合金化以部分去除铜，通过改变大颗粒和一些中等颗粒的形态来增加铂的表面积，使其成为具有许多空隙的“瑞士奶酪”型结构。较小的颗粒保持了其核壳结构。脱合金化对催化剂材料的比活性影响不大，但由于比表面积增大，催化剂的质量活性增加了一倍以上。本报告讨论了这些结果的可能来源。
A carbon-supported, dealloyed platinum-copper (Pt-Cu) oxygen reduction catalyst was prepared using a multi-step synthetic procedure. Material produced at each step was characterized using high angle annular dark field scanning transmission electron microscopy (HAADF-STEM), electron energy loss spectroscopy (EELS) mapping, x-ray absorption spectroscopy (XAS), x-ray diffraction (XRD), and cyclic voltammetry (CV), and its oxygen reduction reaction (ORR) activity was measured by a thin-film rotating disk electrode (TF-RDE) technique. The initial synthetic step, a co-reduction of metal salts, produced a range of poorly crystalline Pt, Cu, and Pt-Cu alloy nanoparticles that nevertheless exhibited good ORR activity. Annealing this material alloyed the metals and increased particle size and crystallinity. TEM shows the annealed catalyst to include particles of various sizes, large (>25 nm), medium (12–25 nm), and small (<12 nm). Most of the small and medium-sized particles exhibited a partial or complete coreshell (Cu-rich core and Pt shell) structure with the smaller particles typically having more complete shells. The appearance of Pt shells after annealing indicates that they are formed by a thermal diffusion mechanism. Although the specific activity of the catalyst material was more than doubled by annealing, the concomitant decrease in Pt surface area resulted in a drop in its mass activity. Subsequent dealloying of the catalyst by acid treatment to partially remove the copper increased the Pt surface area by changing the morphology of the large and some medium particles to a “Swiss cheese” type structure having many voids. The smaller particles retained their core-shell structure. The specific activity of the catalyst material was little reduced by dealloying, but its mass activity was more than doubled due to the increase in surface area. The possible origins of these results are discussed in this report.
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影响因子：
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作者：
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通讯作者：
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影响因子：
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