Carbon monoxide voltammetric oxidation

Figure 11.14 Voltammetric oxidation of carbon monoxide at a gold electrode curve a, an inactive electrode curve b, an activated electrode. Scan rate 0.05 Vs 1 supporting electrolyte, 0.01 M NaOH in 0.1 M K2S04 solution saturated with 100% CO ( 1 mM) electrode area 2.42 cm2. 

The region of the cyclic voltammogram, corresponding to anodic removal of Hathermal desorption spectra of platinum catalysts. However, unlikely the thermal desorption spectra, the cyclic-voltammetric profiles for H chemisorbed on Pt are usually free of kinetic effects. In addition, the electrochemical techniques offer the possibility of cleaning eventual impurities from the platinum surface through a combined anodic oxidation-cathodic reduction pretreatment. Comparative gas-phase and electrochemical measurements, performed for dispersed platinum catalysts, have previously demonstrated similar hydrogen and carbon monoxide chemisorption stoichiometries at both the liquid and gas-phase interfaces (14). 

There is a strong difference between the voltammetric profiles of the carbon monoxide oxidative desorption on a pure platinum single crystal in the presence of an ad-metal species and the same in the absence of an ad-metal species. The carbon monoxide adsorption and oxidation are also different depending on the type of the deposited metal as shown in Figure 11.4. 

The experimental results suggest the following sequence first, a carbon monoxide and water species adsorption on nickel, second, the electrodissolution of nickel is inhibited by the adsorbed carbon monoxide, third, the anodic stripping of the adsorbate occurs at the rising branch of the current vs. potential profile, and this is finally followed by the oxidation of the underlying nickel layers. Thus, the carbon monoxide mass-current intensity signal reaches its maximum before the voltammetric peak that is almost totally determined by the bulk electrodissolution-precipitation process of nickel. A small portion of the remaining adsorbate is oxidized to carbon dioxide induced by the co-adsorbed hydroxyl present at the nickel interface. 

Chen ZF, Jiang YX, Wang Y, Xu JM, Jin LY, Sun SG. Electrocatalytic oxidation of carbon monoxide and methanol at Pt nanoparticles confined in SBA-15 voltammetric and in situ infrared spectroscopic studies. J Solid State Electrochem 2005 9 363-70. 

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