Underpotential Deposition on Single-Crystal Pt Group Metals

Underpotential Deposition on Single-Crystal Pt Group Metals 

Rotating ring-disk electrodes were employed for an anion effect on the Cu underpotential deposition on Pt(lll) in fluoric and perchloric acid solutions, the results of which were discussed in comparison with UHV results of AES and LEED.  

An ex situ EXAFS study was conducted for Cu underpotential deposition on polycrystalline Pt in 0.2mM CUSO4 + 0.5M H2SO4. The iodine-treated Pt was subjected to Cu underpotential deposition, the features of which were observed by EXAFS. ° An EXAFS study of Cu 

Underpotential deposition of Zn on R was seen as adsorption of Zvi ions in 1970, since is as high as 1V, a value that well exceeds the one expected from previous results on various metal combinations of underpotential deposition systems. Recently, Zn underpotential deposition on R was reported in acidic solutions, and then in alkaline solutions. Zn underpotential deposition on Pd was also found in acidic and alkaline solutions. Then cyclic voltammograms of underpotential deposition on three low-index, single-crystal Rs were observed in sulfuric and perchloric acid solutions, as shown in Figs. 27 and 28. In comparing Figs. 27 and 28, Zn underpotential deposition on R seans to take place only on Pt(llO), but not on Pt(lll) and Pt(lOO). Therefore it can be said that a cyclic voltammogram on polycrystalline R was observed on a R(110)-like surface. 

A cyclic voltammogram ofZn underpotential deposition on Pt(llO) in sulfuric acid solution is more reversible than that in perchlorie acid solution with respect to the change of potentials, as shown in Fig. 27. The was evaluated as about 1 V. Since Zn underpotential deposition in acidic solutions was observed in the adsorbed hydrogen region, the pH was increased to separate Zn underpotential deposition from the hydrogen adsorption region. At pH 4.6, Zn underpotential deposition was observed, as shown in Fig. 29. The different cyclic voltammogram appearances of Zn underpotential deposition on Pt(lll) at different pHs is discussed in Section n.4. 

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