COLL 320 |
| To continuation of our previous research on photoelectrochemical properties of GaAs we present photocorrosion inhibition by cetylpyridinium chloride (CPC) surfactant. This material is chemisorbed on GaAs surface from aqueous acidic electrolytes at concentrations of CPC around its critical micelle concentration (CMC). The anodic photogenerated currents of n-GaAs electrode deteriorated due to adsorption of CPC on GaAs; signifying its inhibition. The adsorption of CPC also shifted the onset potential of the photocurrent towards more negative values; that is accounted by the adsorption of the surfactant molecule on GaAs surface via its pyridine aromatic ring. Furthermore, the CPC adsorption did not only decrease the anodic photocurrents, those due to GaAs corrosion, but also decreased the dark cathodic currents of hydrogen evolution. The maximum inhibition efficiency was ~ 63%, obtained by concentration of CPC of 1 x 10-3 M. Above this concentration, the inhibition efficiency decreased; presumably due to desorption of the CPC molecules from the surface GaAs to participate in micelle formation within the electrolyte. When cerrous nitrate was added to the acidic solution of CPC, the anodic photocurrent was stable and did not show any sign of deterioration; revealing that photocorrosion of n-GaAs was inhibited and the generated photocurrent was due to the oxidation of cerrous ions rather than the oxidation of the electrode material itself. |
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Advanced Materials for Conversions and Separations in Energy Applications
6:00 PM-8:00 PM, Monday, August 20, 2007 BCEC -- East Registration, Poster
Division of Colloid & Surface Chemistry |