Photoelectrochemical H2 generation from water using a CoO x /GaN photoelectrode

We report the fabrication of a GaN-based photoelectrode with CoO x as a cocatalyst for the photoelectrochemical H2 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 CoO x /GaN photoelectrode is capable of generating H2 at a quasi-stable rate for at least 20 h. Scanning and transmission electron microscopy analyses of the cocatalyst confirmed that the CoO x particles agglomerate in sparse polycrystalline clusters, which were formed mainly by spinel Co3O4.