Effect of Hydrogen and Oxygen Evolution Cocatalysts on Photocatalytic Activity of GaN:ZnO

Abstract

Abstract The coloading effect of H 2 and O 2 evolution cocatalysts on the overall water splitting reaction was investigated using a solid solution of GaN and ZnO (hereafter termed GaN:ZnO) as a photocatalyst. GaN:ZnO was modified with nanoparticulate Mn 3 O 4 , RuO 2 , and IrO 2 as O 2 evolution cocatalysts and with core/shell‐type Rh/Cr 2 O 3 composites as H 2 evolution cocatalysts. The photocatalytic activity of the coloaded samples for overall water splitting was higher than that of the samples modified with either of the O 2 or H 2 evolution cocatalysts alone. The activity enhancement induced by coloading was comparable for the three O 2 evolution cocatalysts investigated at the optimized loading amounts. Loading of a more efficient Rh/Cr 2 O 3 cocatalyst prepared by adsorption of Rh nanoparticles further improved the photocatalytic activity. It was concluded that a simultaneous improvement in both oxidation and reduction reactions was effective at enhancing the photocatalytic activity of GaN:ZnO, whereas the reduction reactions limited the overall reaction rate of the coloaded system more significantly.