Photoelectrochemical Characterization of p-type InAlP on GaAs for Solar Water Splitting Application

The photoelectrochemical characteristics of p-InAlP grown on GaAs were investigated to exploit the potential of that material future as a photocathode in solar water splitting. The flat band potential was measured, and electrochemical impedance spectroscopy was performed to propose an equivalent circuit model and circuit elements fitted for charge transport analysis. Low photocatalytic activity was attributed to the band alignment with the water redox level. Since the valence band of InAlP is close to the water oxidation level, it causes inefficient hole transport to the counter electrode and the accumulation of holes in the photocathode.