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

Abstract

Abstract Here, a feather‐like Eu‐doped ZnO (particle size ≈ 34.87 µm and Eg ≈ 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 Eg ≈ 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.

Keywords

• europium‐doping
• graphene oxide
• hydrogen generation
• water splitting
• ZnO