Ubiquitous strategy for probing ATR surface-enhanced infrared absorption at platinum group metal-electrolyte interfaces.
Ubiquitous strategy for probing ATR surface-enhanced infrared absorption at platinum group metal-electrolyte interfaces.
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DOI：
10.1021/jp044085s
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发表时间：
2005-04
期刊：
影响因子：
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通讯作者：
Yan-Gang Yan-Yan-Gang-Yan-93057829;Qiaoxia Li;Sheng-Juan Huo;M. Ma;W. Cai;M. Osawa
中科院分区：
文献类型：
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作者：
Yan-Gang Yan-Yan-Gang-Yan-93057829;Qiaoxia Li;Sheng-Juan Huo;M. Ma;W. Cai;M. Osawa
提出了一种用于原位衰减全反射傅立叶变换红外（ATR-FTIR）电化学界面研究的Pt， Pd， Rh和Ru纳米颗粒膜（以下简称纳米膜）的通用两步湿法工艺，该工艺包括在硅棱镜基面上初始化学沉积金纳米膜，随后电沉积所需的铂族金属覆盖层。从磷酸盐或高氯酸电解质中恒电流电沉积Pt， Rh和Pd，或从硫酸电解质中恒电位电沉积Ru，产生足够的“无针孔”覆盖层，这是电化学和光谱表征所证明的。由此获得的铂族金属纳米膜表现出强烈增强的红外吸收。与直接电化学沉积在玻碳和大块金属电极上的相应金属膜相比，观察到探针分子CO的吸收增强表现为正常的单极带形状。扫描隧道显微镜（STM）图像显示，铂族金属的细颗粒沉积在较大尺寸的波状和阶梯状金纳米颗粒周围。这种无处不在的策略有望为扩展ATR表面增强红外吸收光谱开辟广阔的道路，以探索技术上重要的过渡金属的分子吸附和反应，例如成功的实时光谱和电化学监测CO在Pd上的氧化和甲醇在Pt纳米膜电极上的氧化。讨论了与CO共吸附在Pt、Pd、Rh和Ru上的自由水分子的光谱特征。
A versatile two-step wet process to fabricate Pt, Pd, Rh, and Ru nanoparticle films (simplified as nanofilms hereafter) for in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) study of electrochemical interfaces is presented, which incorporates an initial chemical deposition of a gold nanofilm on the basal plane of a silicon prism with the subsequent electrodepostion of desired platinum group metal overlayers. Galvanostatic electrodeposition of Pt, Rh, and Pd from phosphate or perchloric acid electrolytes, or potentiostatic electrodeposition of Ru from a sulfuric acid electrolyte, yields sufficiently "pinhole-free" overlayers as evidenced by electrochemical and spectroscopic characterizations. The Pt group metal nanofilms thus obtained exhibit strongly enhanced IR absorption. In contrast to the corresponding metal films electrochemically deposited directly on glassy carbon and bulk metal electrodes, the observed enhanced absorption for the probe molecule CO exhibits normal unipolar band shapes. Scanning tunneling microscopic (STM) images reveal that fine nanoparticles of Pt group metals are deposited around wavy and stepped bunches of Au nanoparticles of relatively large sizes. This ubiquitous strategy is expected to open a wide avenue for extending ATR surface-enhanced IR absorption spectroscopy to explore molecular adsorption and reactions on technologically important transition metals, as exemplified by successful real-time spectroscopic and electrochemical monitoring of the oxidation of CO at Pd and that of methanol at Pt nanofilm electrodes. The spectral features of free water molecules coadsorbed with CO on Pt, Pd, Rh, and Ru are also discussed.