Platinum electrode potential cycling

In a typical application the oxidation state of upd-tin on a platinum surface electrochemically roughened by fast electrode potential cycling (roughness fac-... 

Diaz et al. [37] and others [38,39] reported the preparation of polyaniline in an aqueous acid solution using a platinum electrode by cycling the potential between —0.2 to 0.8 V versus SCE. 

Fig. 59. CVs of PPy deposited galvanostatically at i = 0.5 mA onto a platinum sheet from a solution of 0.1-M pyrrole in acetonitrile -fO.l-M LiC104 -I- 0.5% water. The first and second cycles and the cycle measured after 17 min of electrode potential cycling are displayed.

Polycrystalline platinum was cleaned by heating in hydrogen-air flame and then dipped in to the electrolyte. The potential was scanned in the electrolyte from 50 mV to 1600 mV for I min, at a scan rate of 10 V/s. For infrared spectroscopy, the electrode was cleaned with filming sulfuric acid followed by the potential cycles described above until the voltammogram became that of clean platinum. 

Figure 2.2 shows the first-scan cyclic voltammogram obtained by a platinum electrode for a 1.0 mM K4[Fe(CN)g] plus O.IOM KCl solution in water. Here, as in all figures in this chapter, potentials are referred to the AgCl (3 M NaCl)/Ag electrode. Generally, the first recorded cycles differ slightly, and only after 3-4 cycles do the CVs approach a constant response. In this experiment, the potential scan is... 

Fig. 8.10. Potentiodynamic i-v profile for a platinum electrode surface in 0.5 M H2S04 solution, showing the effect of potential cycling on cleanup of the surface. The two lines shown are for the first lower" and the twentieth higher sweep. (Reprinted from H. Angerstein-Kozlowska, in Comprehensive Treatise of Electrochemistry, E. Yeager, J. O M. Bockris, B. E. Conway, and S. Sarangapani, eds., Vol. 9, p. 28, Plenum, 1984.)...

The as-received material shows the NMR peak at 1.089 G/kHz that is characteristic of platinum particles exposed to the atmosphere (Fig. 61a) it has been attributed to H2Pt(OH)5 or Pt02. For oxide-supported catalysts, it is removed by thermal treatment under oxygen and hydrogen. The electrocatalysts arc cleaned by electrochemical methods, whereby the sample is used as the working electrode in a three-electrode cell as a reference electrode, 1 M NaCl AgCl j Ag was used. In the first experiments, the as-received material was subjected to extensive potential cycling, but later it... 

An account of early work in this area, i.e., production of a yellowish brown layer of hydrated PtO2 at a platinum electrode in sulfuric acid solution on imposition of an ac component on a dc current, has been given by Altmann and Busch.129 More recent work by Burke and Roche133,134 has demonstrated that quite thick films can be produced in both acid and base on cycling the electrode potential between suitable limits. In the initial work133 oxide growth... 

---