Pb underpotential deposition

Chen C-FI, Washburn N and Gewirth A A 1993 In situ atomic force microscope study of Pb underpotential deposition on Au(111) Structural properties of the catalytically active phase J.Phys. Chem. 97 9754-60... 

Carnal D, Oden P I, Muller U, Schmidt E and Siegenthaler FI 1995 In situ STM investigation of T1 and Pb underpotential deposition on chemically polished Ag(111) electrodes E/ecfroc/r/m. Acta 40 1223-35... 

Melroy and co-workers88 recently reported on the EXAFS spectrum of Pb underpotentially deposited on silver (111). In this case, no Pb/Ag scattering was observed and this was ascribed to the large Debye-Waller factor for the lead as well as to the presence of an incommensurate layer. However, data analysis as well as comparison of the edge region of spectra for the underpotentially deposited lead, lead foil, lead acetate, and lead oxide indicated the presence of oxygen from either water or acetate (from electrolyte) as a backscatterer. 

A similar effect was observed in our work and in the work of others (5), where voltammetry curves changed after extended cycling, particularly if the cathodic sweep was reversed before the full Pb deposition coverage. The observed "cathodic memory effect" may be due to the proposed structural transformation phenomenon and subsequent step density growth, initially facilitated by a high step density on a UHV-prepared or chemically polished (6) Ag(lll) substrate. Post electrochemical LEED analysis on Ag(lll)-Pb(UPD) surfaces provided additional evidence of a step density increase during Pb underpotential deposition, which will be discussed later in this text. (See Figure 3.)... 

Cyclic voltammograms of Pb on low-index single-crystal Au were obsaved in HC104. Voltammograms of Pb underpotential deposition on various index Au faces were observed in 0.01 M HCIO4-1- ImM Pb solution. Since the voltammograms of Pb underpotential deposition are... 

Figure 34. STM image of Pb underpotential deposition on (a) Ag(l II) in 0.0IAfHCIO4 + lOmAf at A = 0.24 V and (b) on Ag(JOO), (From Ref, 112 with permission of Electrvchimica Acta.)...

Figure 37. An STM ima of Pb underpotential deposition on Ag(l 11) in O.OIA/HCIO4 + 5mA/Pb taken at A = 0.125 V. The image size is 12.0 x 12.0 nm and the details are in the text. (From Ref. 113 with permission from Electrochimica Acta.)...

The effect of acetate, citrate, and thiourea on Pb underpotential deposition on Ag(lll) has been studied. The effects of the anionic character of the additives were discussed in relation to changes in voltammograms. The two-dimensional phase transformation was also discussed. The influence of various additives such as dimethylfluoride (DMF) and pyridine on cyclic voltammograms of Cu underpotential deposition on Pt(lll) was observed. Cu underpotential deposition on Pt(lll) was studied in the presence of crystal violet, coumarin, and hydroquinone. ... 

Melroy and co-workers have obtained the EXAFS spectrum of Pb underpotentially deposited on a silver (111) electrode. In this case, no Pb/Ag... 

The results of this STM study, presented in more detail elsewhere [4], are summarized schematically in Fig. 2 in correlation with the typical cyclic voltammogram of Pb underpotential deposition observed at macroscopic, chemically polished Ag(lll) electrodes in perchlorate-containing electrolyte [12]. 

Fig.2. Schematic presentation of the local progress of Pb underpotential deposition at monoatomic pits, monoatomic islands, and stepped terrace domains of non-ideal chemically polished Ag(l 11) electrodes [4]. For fiarther explanation see the text.

Figure 4 shows the resulting data-set from the combined EIS-EQCM study of Pb underpotential deposition (UPD) on Ag Au in 0.1 M HCIO. Preparation and characterization of the Ag yAu surface were reported previously by Berkes et al. (Berkes, Maljusch, Schuhmann, and Bondarenko 2011). Figures 4a and 4b show the extended Bode plots for the EIS measurement of the Pb UPD process. The onset of Pb UPD can be observed at around -0.55 V (MMS) in the cathodic scan. The classic adsorption model was elucidated to be the most appropriate model for the Pb UPD process (Fig. 4c). Figure 4d illustrates the quality of fit of the experimental data to the selected equivalent circuit at selected electrode potentials. Fitting of the EIS data was performed with software reported in (Pomerantsev 2005). 

Rajeshwar and co-workers performed photocatalytic underpotential deposition of Cd and Pb onto the surface of Se-modified Ti02 particles to prepare CdSe/Ti02 and PbSe/Ti02 composites [97, 98]. The Se-modified Ti02 particles were prepared themselves by UV illumination of titania particles in a Se(fV)-containing aqueous solution. The photocatalytic UPD of Cd and Pb on the bare Ti02 surface was found... 

Hagans P, Homa A, Yeager E. 1979. In situ LEED-Auger-thin layer electrochemical studies of the underpotential deposition of Pb on Au single-crystals. J Electrochem Soc 126 (3) C147. 

The electrochemical quartz crystal microbalance (EQCM) method was first used to study underpotential deposition in 1988 for Pb, Bi, Cu,... 

Equations (27) and (28) give mountainlike curves of j against t, and s against t of underpotential depositions of Pb on Ag single crystals were... 

The overpotential three-dimensional nucleation process is affected by the change of prepolarization potential in the underpotential deposition region of Pb on Ag. When A is low (potential is close to feq), the rate of the... 

In this chapter, hydrogen adsorption, particularly observed on Pt electrodes, was not treated as an underpotential deposition phenomenon. However, from a theoretical point of view, it may provide a breakthrough insight into underpotential deposition. Since the underpotential deposition ofM on M is quite characteristic among different combinations of M and M, together with a change in the kind of anions in the solution, a theoretical approach, which requires simplification, is still limited, and more experimental clarification is needed for theoretical work. However, the jellium model was successfully used to describe the lattice contraction of adsorbate T1 and Pb on Ag(lll) as underpotential deposition. ... 

Pb Lead, and particularly underpotentially deposited Pb, exhibits electrocatalytic properties in numerous electrode processes. The model reaction can be oxygen reduction with slow step of peroxide reduction ]374-376] or reduction of nitrobenzene and other nitrocompounds [377, 378]. In the case of... 

Fig. 5 Underpotential deposition of Pb on Ag(l 11) electrode from 0.1 M HCIO4 solution containing 1 x 10 Pb + [189].

Fig. 14. Activity of Pt for hydrogen evolution in 1 M HC104 as a function of the coverage with underpotential deposited Pb. A change in mechanism with Pb coverage is indicated. After ref. 303, by permission of Pergamon Press.

Lead and mercury are deposited as micron-sized clusters, predominantly at intercrystallite boundaries [105] so does lithium from the polyethylene oxide solid electrolyte. What is more, Li intercalates into the sp2-carbon [22, 138], Thus, observations on the Li intercalation and deintercalation enable one to detect non-diamond carbon on the diamond film surface. Copper is difficult to plate on diamond [139], There is indirect evidence that Cu electrodeposition, whose early stages proceed as underpotential deposition, also involves the intercrystallite boundaries [140], We note that diamond electrodes seem to be an appropriate tool for use in the well-known electroanalytical method of detection of traces of metal ions in solutions by their cathodic accumulation followed by anodic stripping. The same holds for anodic deposition, e.g. of, Pb as PbCh with subsequent cathodic reduction [141, 142], Figure 30 shows the voltammograms of anodic dissolution of Cd and Pb cathodically predeposited from their salt mixtures on diamond and glassy carbon electrodes. We see that the dissolution peaks are clearly resolved. The detection limit for Zn, Cd, and Pb is as low as a few ppb [143]. 

Fig. 61 Underpotential deposition of lead on gold from a solution of 1.0 mM Pb ClO ) in 1.0 MllClO. v = 10 mV/sec. Two underpotential (UPD) deposition and dissolution peaks are shown. Data from Deakin and Melroy, J. Electroanal. Chem. 239, 321 1988).

Watanabe T, Yanagihara N, Honda K, Pettinger B, Moerl L (1983) Effects of underpotentially deposited T1 and Pb submonolayers on the surface-enhanced Raman-scattering (SERS) from pyridine at Ag electrodes. Chem Phys Lett 96(6) 649-655... 

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