Accumulation layer formation at n-gallium arsenide/electrolyte interface: photoluminescence probe of the kinetic barrier for hydrogen evolution reaction

Abstract

The photoluminescence intensity of the n-GaAs electrode increased with the increase of forward bias when the potential was more negative than the flat band potential, suggesting the accumulation of electrons at the surface caused by a kinetic barrier for hydrogen evolution reaction (HER). The surface treatment by a noble metal (Pt) removes the kinetic barrier for HER, leading to a significant increase of HER rate and no dependence of the PL intensity, i.e., no accumulation of electrons. Thus, an etched semiconductor/electrolyte interface behaves more like a MIS structure rather than the Schottky junction.