Oxidation-reduction cycle surface cleaning with

SERS due to pyridine on Au electrode surfaces appears to arise from the adsorption of pyridine in or on surface carbon present after the oxidation-reduction cycle [25,26], Anodically roughened Ag electrode surfaces, which were subsequently cathodically cleaned, exhibited no SERS from pyridine. This confirms that the SERS-active phase is carbon-pyridine and not pyridine alone. In ultrahigh vacuum, SERS can be induced in pyridine by coadsorbing pyridine with CO [27], The effect depends on the type of silver surface and involves shifts in the peak positions and intensities of some of the vibrational modes. SERS peaks were not observed at 2100 cm 1 at the position of the C O stretching mode of CO. A possible interpretation is that surface complexes are formed between pyridine and CO molecules at the active or hot sites on the silver surface. 

The gold minigrid electrode in the thin-layer cell is first cleaned in nitric acid, acetone, and then in water. Subsequently, the cell is filled with a deaerated 1.0 M HCIO4 solution and the electrode is treated by an oxidation-reduction cycle until the gold electrode is confirmed to be clean by comparison with usual characteristics of a clean gold electrode surface [9]. 

Much work has been published on the dissolution of iron oxides in connection with the iron cycle in geochemistry, decontamination processes or the clean-up of industrial facilities. We have already seen that strong chelating agents such as EDTA or amino acids can adsorb on the surface of oxides and promote their dissolution because they can form anion complexes that are more stable than the oxide [52,63,64], Citrates and oxalates, among others, act in a similar way [65], Dissolution of oxides is markedly accelerated if oxidation-reduction processes occur in conjunction with anion adsorption [66]. The adsorption of ascorbate on hematite is a good example [67] (Figure 9.16). The reduction of ferric ions is shown... 

A clean silver surface will adsorb oxygen in a dissociated form. LEED studies show that on the Ag(l 11) face oxygen adsorbs to form a stable (4 x 4) superstructure. This has been interpreted as a coincidence lattice between the Ag(lll) plane and the (111) plane of silver(i) oxide. There is evidence that oxygen adsorption on faces other than Ag(lll) results in the formation of Ag(l 11) facets. " Incorporation of oxygen into the subsurface appears to be rather slow in the presence of molecular oxygen, but alternate cycles of oxidation and reduction with CO results in the build up of a thin subsurface layer of oxidized silver. ... 

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