Photocorrosion inhibition -ofn-GaAs in acidified aqueous iodide solution

Abstract

AbstractThe photocorrosion of n-GaAs electrodes in aqueous solutions represents one of the most important factors limiting their application in solar energy conversion. In continuation of previous studies, the corrosion of n-GaAs has been investigated in 0·5M H2SO4 using a pllOtoelectrochemical cell. Illumination of the n-GaAs anode with white light of intensity 20 mW cm-2 generated a saturation photocurrent of 27 mA cm-2 at biasing voltages more positive than +0·45 V(SCE). This current corresponded to hydrogen discharge at the platinum counter electrode and to oxidation of the GaAs surface. When 0·01-6·0M LiI was added to the H2SO4 solution, 12 was formed at the n-GaAs electrode and dissolved in the iodide solution. The onset potential of the photocurrent (Ep) shifted from -0·36 to -0·73 V(SCE) as the concentration was varied from 0·01 to 6·0M I-. Addition of I-3 shifted Ep to more positive values. The extent of corrosion was studied by comparing the ratios of photogenerated I2 and H2. In 0·01, 1·0, and ...