Electrochemical stability and restructuring and its impact on the electro-oxidation of CO: Pt modified Ru(0001) electrodes
Electrochemical stability and restructuring and its impact on the electro-oxidation of CO: Pt modified Ru(0001) electrodes
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DOI：
10.1016/j.susc.2014.05.022
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发表时间：
2015-01-01
期刊：
影响因子：
1.9
通讯作者：
Behm, R. J.
中科院分区：
文献类型：
--
作者：
Engstfeld, A. K.;Klein, J.;Behm, R. J.
在电化学测量过程中的Pt修饰的Ru（0001）电极表面，这是制备和表征在超高真空（UHV）条件下，和CO氧化反应的重组的影响进行了研究，在一个设置相结合的表面制备和超高真空条件下的扫描隧道显微镜表征（UHV-STM）和电化学流通池测量。研究了裸Ru（0001）和Pt单层岛修饰Ru（0001）电极，并与Pt 0.3Ru 0.7/Ru（0001）单层表面合金进行了比较。将在基础电解质（0.5 M H2SO 4）中循环至0.90 V-RHE时进行的本体CO氧化测量与在电势循环至1.05 V-RHE后进行的类似测量进行比较，我们发现电流-电压特性的显著差异，在后一种情况下，在正向扫描中的低电势处具有明显的新峰，其中心在0.67 V-RHE。电催化测量之前和之后进行的STM成像显示，在电位循环至1.05 V-RHE时，Pt单层岛修饰的Ru（0001）表面发生了明显的重组，而循环至0.90 V-RHE时保持了双金属表面的原始结构和形态。相反，对于裸Ru（0001）电极，在电位循环至0. 9V-RHE时已经观察到台阶的重构。这些研究结果的电化学稳定性的电极，以及对CO的氧化反应的机理的理解上的影响进行了讨论，在PtRu电极表面和不同的单和PtRu纳米结构的活性。(C)2014爱思唯尔有限公司版权所有。
Structural modifications during electrochemical measurements on well defined Pt modified Ru(0001) electrode surfaces, which were prepared and characterized under ultrahigh vacuum (UHV) conditions, and the influence of the restructuring on the CO oxidation reaction have been investigated in a set-up combining surface preparation and scanning tunneling microscopy characterization under UHV conditions (UHV-STM) and electrochemical flow cell measurements. Bare Ru(0001) and Pt monolayer island modified Ru(0001) electrodes with different Pt coverages were investigated, together with a Pt0.3Ru0.7/Ru(0001) monolayer surface alloy for comparison. Comparing bulk CO oxidation measurements performed upon cycling in base electrolyte (0.5 M H2SO4) to 0.90 V-RHE with similar measurements performed after potential cycling to 1.05 V-RHE, we find pronounced differences in the current-voltage characteristics, with a distinct new peak at low potentials in the positive-going scan in the latter case, which is centered at 0.67 V-RHE. STM imaging performed before and after the electrocatalytic measurements revealed a distinct restructuring of the Pt monolayer island modified Ru(0001) surfaces upon potential cycling to 1.05 V-RHE, while cycling to 0.90 V-RHE maintains the original structure and morphology of the bimetallic surface. In contrast, for the bare Ru(0001) electrode, restructuring of steps is observed already upon potential cycling to 0.9 V-RHE. Implications of these findings on the electrochemical stability of the electrodes as well as on the mechanistic understanding of the CO oxidation reaction on bimetallic PtRu electrode surfaces and on the activity of different mono- and bimetallic nanostructures are discussed. (C) 2014 Elsevier B.V. All rights reserved.