P-N Heterojunction System Eu-Doped ZnO@GO for Photocatalytic Water Splitting

Here, a feather-like Eu-doped ZnO (particle size ≈ 34.87 µm and E _g ≈ 3.13 eV) nanoassembly is synthesized by using the capping agent cetyltrimethylammonium bromide-supported hydrothermal method. The Eu-doped ZnO is loaded onto the graphene oxide (GO) surface as Eu-doped ZnO@GO (particle size ≈ 23.07 µm and E _g ≈ 0.79 eV) and applied to measure the photocatalytic water splitting activity in 20% CH₃OH under a 300 W Xe light source. Eu-doped ZnO@GO exhibits the higher hydrogen generation activity of 255.8 µmol h^-1 g^-1 that is 159 and 1.5 times more than the pristine GO and Eu-doped ZnO systems, respectively. Eu-doped ZnO enhances the photocatalytic activity of GO because the p-n junction formed between GO and Eu-doped ZnO might support the charge-transfer and suppress charge recombination. The light harvesting power of Eu-doped ZnO@GO makes the charge transfer smooth through the GO network. Surface photovoltage and electrochemical impedance studies of the Eu-doped ZnO@GO composite, reveal that GO acts as the p-type semiconductor and Eu-doped ZnO works as an n-type semiconductor and their interface facilitates the p-n junction to ease charge separation and results in enhanced the water-splitting efficiency.