Electrochemical Stability of p-GaInP2 in Aqueous Electrolytes Toward Photoelectrochemical Water Splitting

With an eye toward developing a photoelectrochemical system for water splitting using p-GaInP₂, the electrochemical stability of p-GaInP₂, was studied in 10 M KOH, 3 M H₂SO₄, and a phosphate buffer of pH 7. It was found that in the dark, the p-GaInP₂ electrode is susceptible to corrosion in all investigated solutions. Upon illumination, the anodic corrosion current increases. Under cathodic polarization in 10 M KOH, the p-GaInP₂ electrode shows saturated photocurrent density, however the photocurrent slowly decreases with time due to the precipitation of an indium-enriched oxide. In 3 M H₂SO₄, the anodic process can be inhibited under relatively low cathodic potentials, and stable photocurrnents can be obtained. In neutral solution, p-GaInP₂ is coverd by a semi-insulating oxide film and the observed photocurrent densities are much lower than those in 10 M KOH and 3 M H₂SO₄.