Synthesis of ZnO/rGO nanocomposites by wet impregnation method for photocatalytic performance against RhB dye and 4-chlorophenol under UV light irradiation

ZnO nanoparticles, known as one of the potential materials for photocatalytic application, were synthesized by template/surfactant-free hydrothermal method and annealed at different temperatures. Annealing the ZnO at 400 °C modified the rod-like structures into irregular shaped structures. Further, using wet impregnation method ZnO/reduced graphene oxide (rGO) nanocomposites were prepared for various amounts of rGO. Field emission scanning electron microscopy (FESEM) analysis revealed that ZnO/rGO (6 mg) nanocomposites contain both ZnO and rGO nanoparticles. Optical band gap of the as-synthesized ZnO nanoparticles was slightly shifted from 3.09 to 3.02 eV in ZnO/rGO (6 mg) nanocomposites. Photoluminescence spectral analysis showed that the electron–hole pair recombination rate is effectively suppressed in the ZnO/rGO (6 mg) nanocomposites. Further, the photocurrent measurements revealed that ZnO (annealed at 400 °C) acquires a photocurrent of 2.8 μA/cm2 and is increased to 4.8 μA/cm2 for ZnO/rGO (6 mg) nanocomposites. UV light irradiation exhibited that ZnO nanoparticles annealed at 400 °C show 94% degradation efficiency against Rhodamine B dye for 120 min. Further, ZnO/rGO (6 mg) nanocomposites acquired degradation efficiency of 94% against Rhodamine B dye for 20 min with a better cycling stability up to five cycles.