Sucrose-derived carbon template-assisted synthesis of zinc oxide hollow microspheres: Investigating the effect of hollow morphology on photocatalytic activity

ZnO hollow microspheres were successfully prepared using a sucrose-derived carbon template-assisted hydrothermal method. The synthesized microspheres were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, UV–visible diffuse reflectance spectroscopy, field-emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The field-emission scanning electron microscopy results showed that the shell of hollow microsphere was composed of aggregated ZnO nanoparticles, whereas the sucrose-derived carbon core decomposed during calcination, leaving a hollow interior. X-ray diffraction analysis verified the crystal structure of the ZnO hollow microspheres with a crystallite size of 39.6 nm. ZnO nanoparticles with a similar crystallite size (40.1 nm) were obtained via a polyvinylpyrrolidone-assisted sol–gel method. The photocatalytic efficiency and effect of the hollow morphology of these catalysts for rhodamine blue degradation were studied under ultraviolet light irradiation. Both ZnO hollow microspheres and ZnO nanoparticles showed excellent photocatalytic activity although minimal amount of these catalysts (only 2 mg) was used in the experiment. The ZnO hollow microspheres showed 10% higher efficiency than ZnO nanoparticles, owing to their nanoporous structure, higher surface area, and easy formation of OH radicals.