Silica-coated zinc oxide nanocomposite: a novel green synthesis using rice husk as a source of silica nanoparticles

Abstract

This study presents a green synthesis method for producing silica-coated zinc oxide (ZnO/SiO2) nanocomposites using rice husk as a silica source. The synthesis involves preparing ZnO nanoparticles via a precipitation method, followed by extracting and incorporating silica from rice husk through acid-base treatment. The resulting ZnO/SiO2 nanocomposites were characterized using X-ray diffraction (XRD), Fourier-transform infrared (FTIR), Brunauer-Emmett-Teller (BET) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy. XRD analysis confirmed the formation of the wurtzite hexagonal phase of ZnO and the amorphous nature of SiO2. BET analysis revealed a significant increase in surface area for ZnO/SiO2 (204 m2/g) compared to ZnO alone (33 m2/g), attributed to the mesoporous structure of the SiO2 shell. SEM images showed reduced nanoparticle agglomeration after silica composing. PL spectroscopy demonstrated enhanced UV emission and a reduction in defect-related emissions in the ZnO/SiO2 nanocomposite, indicating improved charge separation and reduced recombination. This green synthesis approach, which utilizes rice husk, offers an eco-friendly and cost-effective method for fabricating high-performance ZnO/SiO2 nanocomposites, making them suitable for various photocatalytic applications. Rhodamine B (Rh-B) dye photodegradation investigations using UV light interaction in aqueous media revealed 31.48% and 99.04% of ZnO and ZnO/SiO2 nanocomposite present, respectively. Using 0.015 g of photocatalyst (ZnO/SiO2) results in the greatest photodegradation (99.04%) in neutral media (pH 7). Even after four consecutive cycles with the recycled photocatalyst, the dye’s photodegradation efficiency stayed high during the reusability cycles.