Towards the quantification of the chemical mechanism of light-driven water splitting on GaN photoelectrodes.

We present results from a study addressing the unbiased water-splitting process and its side reactions on GaN-based photoelectrodes decorated with NiO, FeO, and CoO nanoparticles. Observations involving physicochemical analyses of liquid and vapour phases after the experiments were performed in 1 M NaOH under ambient conditions. A water-splitting process with GaN-based photoelectrodes results in the generation of hydrogen gas and hydrogen peroxide. Quantification of the water-splitting chemical mechanism gave numerical values indicating an increase in the device performance and restriction of the GaN electrocorrosion with surface modifications of GaN structures. The hydrogen generation efficiencies are (bare GaN) = 1.23%, (NiO/GaN) = 4.31%, (FeO/GaN) = 2.69%, and (CoO/GaN) = 2.31%. The photoelectrode etching reaction moieties / are 11.5%. 0.21%, 0.26% and 0.20% for bare GaN, NiO/GaN, FeO/GaN, and CoO/GaN, respectively.