Surface states in the band-gap for Pt-deposited p-InP photoelectrochemical cells

Electrochemical Passivation of Homoepitaxial InP (100) Thin Films for Light Induced Hydrogen Evolution: A Synchrotron Radiation Photoelectron Spectroscopy Study

“…This is result of the photo-decomposition reaction [1]. The growth of In 2 O 3 film can be explained in terms of oxidation of metallic In according to reactions [2] and [3]. The formation of indium oxide from reaction [4] does not seem probable, because it would be in contradiction with the simultaneous decrease of the phosphate signal.…”

“…P-type InP is known to be a promising candidate as photoelectrode in solar conversion devices for light induced hydrogen generation. This isjustified by the energy position of the band edges and the near-optimum energy gap of 1.34 eV (1) with a theoretical maximum achievable photopotential of 0.9 eV, disregarding possible interfacial dipoles that are known to alter band alignments in solid state and photoelectrochemical devices (2,3).It was observed that the electrochemical cycling in HCl solution in the cathodic region enhances the photoelectrochemical activity of p-InP(111) surfaces (4); the cathodic photocurrent increases with each further cycle up to reach a stationary value after several tens of cycles. The effect was, however, not observed if the cyclic polarization is performed under the same potential and illumination conditions in H 2 SO 4 .…”