Effect of Surface Composition on Electrochemical Oxidation Reaction of Carbon Monoxide and Ethanol of PtxRh1−x Solid Solution Electrodes

IF 2.3 Q3 ELECTROCHEMISTRY
Nguyen Trung Kien, Haruki Yara, Masanobu Chiku, E. Higuchi, Hiroshi Inoue
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引用次数: 0

Abstract

PtxRh1−x (x = 0.76, 0.54, and 0.27) solid solutions were prepared by arc-melting. For these solid solutions, the lattice constant was linearly related to the Pt content. The surface compositions of the solid solutions determined by X-ray photoelectron spectroscopy were quite similar to their bulk compositions estimated by energy dispersive X-ray spectroscopy. The CO-stripping voltammograms demonstrated that the onset potential of CO oxidation current density (Eonset) shifted negatively as the surface Pt content decreased, suggesting an increased CO-poisoning resistance. Linear sweep voltammograms of the solid solution electrodes in an Ar-saturated (1 M ethanol + 0.1 M HClO4) solution exhibited that the onset potentials of ethanol oxidation reaction (EOR) current for all solid solution electrodes were lower than of a Pt electrode, and Pt0.54Rh0.46 gave the highest specific activity (SA) of 312 μA·cm−2, which was about 1.8 and 2.5 times higher than the SAs of Pt and Rh, respectively. In situ infrared reflection-absorption spectra exhibited that the Pt0.54Rh0.46 electrode had the bands due to the linear-bonded CO on Pt and bridge-bonded CO on Rh as EOR intermediates around 0.2 V vs. the reversible hydrogen electrode, but the band due to the linear-bonded CO on Rh was not observed even at 0.6 V, suggesting that the existence of the adjacent Pt-Rh sites and the preferential formation of bridge-bonded CO on Rh accelerated the C-C bond cleavage and improved the EOR activity.
表面成分对 PtxRh1-x 固溶体电极的一氧化碳和乙醇电化学氧化反应的影响
通过电弧熔化法制备了 PtxRh1-x(x = 0.76、0.54 和 0.27)固溶体。这些固溶体的晶格常数与铂含量成线性关系。用 X 射线光电子能谱测定的固溶体表面成分与用能量色散 X 射线能谱估计的体积成分非常相似。一氧化碳剥离伏安图表明,一氧化碳氧化电流密度的起始电位(Eonset)随着表面铂含量的降低而负移,这表明一氧化碳中毒电阻增加。固溶体电极在 Ar 饱和(1 M 乙醇 + 0.1 M HClO4)溶液中的线性扫描伏安图显示,所有固溶体电极的乙醇氧化反应(EOR)电流起始电位均低于铂电极,其中 Pt0.54Rh0.46 的比活度(SA)最高,为 312 μA-cm-2,分别是 Pt 和 Rh 比活度的 1.8 倍和 2.5 倍。原位红外反射吸收光谱显示,与可逆氢电极相比,Pt0.54Rh0.46 电极在 0.2 V 左右出现了铂上线性键合 CO 和 Rh 上桥键合 CO 作为 EOR 中间产物产生的带,但即使在 0.6 V 时也没有观察到 Rh 上线性键合 CO 产生的带,这表明相邻 Pt-Rh 位点的存在和 Rh 上桥键合 CO 的优先形成加速了 C-C 键的裂解,提高了 EOR 活性。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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