Effects of La-doping on charge separation behavior of ZnO:GaN for its enhanced photocatalytic performance

In this work, lanthanum (La) has been proven as an effective space charge layer modifier to promote efficient photogenerated charge carrier separation for ZnO:GaN solid solution photocatalysts with enhanced photocatalytic water-splitting performance. Photogenerated electron-hole pairs are effectively separated due to the increase of the thickness of the space charge layer after La-doping. The stable photocatalytic activity of the ZnO:GaN solid solution photocatalysts for overall water-splitting was remarkably enhanced by about 3.4 times when the La-doping concentration was 3% in atom ratio. The maximum apparent quantum efficiency of the La-doped (3% in atom percentage) ZnO:GaN solid solution photocatalyst for photocatalytic water oxidation was up to 14.5% at 350 nm without loading of any co-catalyst.