Efficient photocatalytic degradation of methylene blue by heterostructured ZnO-RGO/RuO₂ nanocomposite under the simulated sunlight irradiation

We report an ZnO-RuO₂/RGO ternary nanocomposite synthesized via a hydrothermal method combined with a homogeneous precipitation method. Morphological and elemental analysis demonstrates that ZnO nanosheets were anchored on the graphene nanosheets surrounded by RuO₂ nanoparticles. The ZnO-RGO/RuO₂ nanocomposites possessed the extended light absorption range and show remarkably enhanced photocatalytic activity toward methylene blue (MB) under the simulated sunlight irradiation as compared to bare-ZnO and the optimum binary ZnO-RGO and ZnO-RuO₂ nanocomposites. We have observed complete degradation of MB in 180, 150, 90, and 60 min for ZnO, ZnO-RuO₂, ZnO-RGO, and ZnO-RGO/RuO₂ nanocomposites respectively. The enhanced photocatalytic performance in ZnO-RGO/RuO₂ is ascribed to increased light absorption and efficient charge separation of the photogenerated carriers and that it prolonged the lifetime of the electron-hole pairs due to the chemical bonding between ZnO, RuO₂ and graphene nanosheets. In addition to the excellent photocatalytic degradation properties, the synthesized samples also exhibited a strong yellow emission, which implies that these nanocomposites may find application as yellow components in near UV-white LEDs. These attractive features make the ZnO-RuO₂/RGO nanocomposite a promising recoverable photocatalyst for practical use in wastewater treatment and fabrication of near UV-white LEDs.