Abstract
We report the fabrication of a GaN-based photoelectrode with CoOx as a cocatalyst for the photoelectrochemical H-2 generation from water. We confirmed that the cocatalyst prevented the GaN photocorrosion partially during the water photoelectrolysis reaction and that it has a superior performance when it is deposited as particles instead of as a thin film. We demonstrated that the CoOx/GaN photoelectrode is capable of generating H-2 at a quasi-stable rate for at least 20 h. Scanning and transmission electron microscopy analyses of the cocatalyst confirmed that the CoOx particles agglomerate in sparse polycrystalline clusters, which were formed mainly by spinel Co3O4. (C) 2019 The Japan Society of Applied Physics