Judicial design of graphene based nanocomposite harvesting UV-Visible spectrum: Efficient, eco-friendly solar photocatalyst for industrial waste management

Abstract

The UV-Visible light reaping graphene based simple nanocomposite was designed by sensible choice and optimization of two constituents of the composite. The hydrothermally synthesized nanopetals of ZnO flower were decorated on reduced graphene oxide (rGO) nanosheets. The absorptivity of ZnO was improved by aptly dispersion on rGO in the nanocomposites, harmonized with solar spectrum maximum (2.4 eV). Even though ZnO in nanoform is a strong UV absorber, our synthesized ZnO nanoflower showed a broad absorptivity covering UV and visible spectral range due to development of different energy states accompanied with various crystal defects. Development of rGO/ZnO composites with optimized ratio of constituents results in a board-range solar absorber (200–800 nm). The intensification in the luminescence accompanied by a reduction in the radiative lifetime of ZnO due to formation of nanocomposite implies a charge transfer process from LUMO levels of rGO to the conduction band of ZnO. Well-tuned absorptivity causing an ample of photogenerated carriers inside the nanocomposite and easy charge transfer between duo make the nanocomposite an efficient solar photocatalyst. Methodical and comparative studies of photocatalytic performance of our designed solar photocatalyst in degradation of cationic and anionic dyes were tested. The best performance was exhibited by 10rGO/ZnO nanocomposite [GO: Zn(NO3)2·6H2O ~ 0.0035 in reaction medium] to degrade the cationic dyes like Safranin O (78%) and Rhodamine 6G (65%) under white light irradiation. Suitable strategy of synthesizing the composite explored an environment-friendly, low-cost, efficient solar photocatalyst for industrial waste management.