Electrochemical Dealloying of Bimetallic ORR Nanoparticle Catalysts at Constant Electrode Potentials
Electrochemical Dealloying of Bimetallic ORR Nanoparticle Catalysts at Constant Electrode Potentials
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DOI：
10.1149/2.0621504jes
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发表时间：
2015
影响因子：
3.9
通讯作者：
S. Rudi;Lin Gan;Chunhua Cui;Manuel Gliech;P. Strasser
中科院分区：
文献类型：
--
作者：
S. Rudi;Lin Gan;Chunhua Cui;Manuel Gliech;P. Strasser
脱合金，即，选择性浸出的Pt基氧还原反应（ORR）纳米颗粒催化剂已经在PEM燃料电池的单电池中证明了先前未实现的初始反应性和性能耐久性。去合金化通常使用酸中的自由腐蚀或电化学循环来实现。在这里，我们探讨了在5-7 nm和>20 nm尺寸范围内的PtNi 3纳米合金纳米颗粒在恒定电极电位下的去合金化。我们调查如何在四个不同的电极电位Ni溶解影响的组合物，形态和表面粗糙度的脱合金催化剂。电极电位覆盖氢吸附区、双电层区和氢吸附区，以考察吸附层是否影响脱合金催化剂的特性。我们发现，大的合金纳米粒子总是脱合金成多孔纳米粒子与一个相对较低的Ni摩尔比为0.4，而较小尺寸的颗粒显示非多孔固体核壳结构与Ni原子%和电位之间的单调依赖。我们提供的证据表明，脱合金催化剂表面的存在/不存在的氢或含氧化合物的吸附adlayers的强烈影响。特别是，数据表明，吸附物adlayers修改之间的平衡Ni溶解和Pt表面扩散的脱合金过程中，导致粗糙的催化剂表面与增强的表面积值。© 2015电化学学会。[DOI：10.1149/2.0621504jes]版权所有。
Dealloyed, that is, selectively leached Pt-based oxygen reduction reaction (ORR) nanoparticle catalysts have demonstrated previously unachieved initial reactivity and performance durability in single cell of PEM fuel cells. Dealloying is typically achieved using free corrosion in acid or electrochemical cycling. Here, we explore dealloying at constant electrode potentials of PtNi3 bimetallic alloy nanoparticles at 5–7 nm and >20 nm size ranges. We investigate how Ni dissolution at four distinct electrode potentials affects the composition, morphology, and surface roughness of the resulting dealloyed catalysts. The electrode potentials cover the hydrogenadsorption, the double layer region, and the oxygenate adsorption region to examine whether adlayers affect the characteristics of the dealloyed catalysts. We show that large alloy nanoparticles invariably dealloy into porous nanoparticles with a relatively low Ni molar ratio of 0.4, while the smaller size particles show non-porous solid core-shell structures with a monotonic dependence between Ni at% and potential. We provide evidence that the dealloyed catalyst surface is strongly influenced by the presence/absence of adsorbed adlayers of hydrogen or oxygenates. In particular, data suggest that adsorbate adlayers modify the balance between Ni dissolution and Pt surface diffusion during the dealloying process resulting in rougher catalyst surfaces with enhanced surface area values. © 2015 The Electrochemical Society. [DOI: 10.1149/2.0621504jes] All rights reserved.