Mesoporous ZnO nanoclusters as an ultra-active photocatalyst

Morphology modulation of nanostructured materials are highly crucial for various applications including photocatalysis, drug delivery, etc. In this study, mesoporous zinc oxide (ZnO) nanoclusters (MZN) were synthesized via a simple, cost-effective, low-temperature wet chemical route and further sucessfully utilized for photodegradation of Rhodamine B (RhB). Firstly, polystyrene (PS) nanospheres (∼300 nm) were prepared by polymerization of styrene in aqueous solvent. Then the MZN were achieved by formation of ZnO nanoparticles-shell over the surface of PS nanospheres via esterification of zinc acetate dihydrate in isopropyl alcohol followed by toluene dissolution of PS core. The as-synthesized MZN were spherically-shaped, porous in nature with a diameter of ∼ 400 nm and composed of well-arranged highly-crystalline ZnO nanoparticles (∼ 5 nm). The MZN also exhibited a high surface area of 78.3±5.4 m² g^-1 and an average pore diameter of ∼26 nm. Furthermore, this unique structure demonstrates an expeditious photodegradation of RhB under UV illumination, monitored by UV-visible spectroscopy at different time intervals until the dye was completely degraded to colorless end products. Fast RhB decomposition was observed with a degradation rate of ∼98% within initial 40 min which can be attributed to the porous nature, large specific surface area and excellent electron accepting features of the engineered nanoclusters.