Reduction of H₂O₂ at CuInSe₂ (Photo)cathodes: I. Characterization of the Electrode–Electrolyte Interface

This study reports electrochemical phenomena observed during reduction of H2O2 at n– and p–CuInSe2(photo)cath–odes in alkaline medium (pH 9 to 10). After cycling the electrode potential in a given potential range, pronounced hysteresis is observed between the two half–cycles of the voltammetry. At both n– and p–materials, during the positive sweep a pronounced increase of the cathodic current is observed at potentials positive of about –0. 8 V. In the potential region corresponding to the HU branch with negative slope, the n– and p–type materials show inverted photocurrents. The photocurrent response is complex showing, e.g., nonproportionality to photon flux and changes in sign. These phenomena are discussed with a qualitative model in terms of changes of the interfacial reactivity caused by the formation of catalytic copper sites on the surface. which kinetically facilitate the process of H2O2 reduction.