Novel and solvent-free cochineal-assisted synthesis of Ag–Al₂O₃ nanocomposites via solid-state thermal decomposition route: characterization and photocatalytic activity assessment

Herein, silver–alumina nanocomposites have been synthesized via simple, novel, solvent-free and template-less solid-state thermal decomposition using cochineal powder as novel starting reagent for the first time. AgNO₃ and Al(OH)₃ were utilized as silver and aluminum source, respectively. The prepared Ag–Al₂O₃ nanostructures were characterized extensively by means of X-ray diffraction, energy-dispersive X-ray analysis, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and UV–Vis spectroscopy. Effect of reaction time, temperature and cochineal powder on morphology and particle size of prepared products was investigated. The results exhibited that in presence of cochineal powder, as-prepared nanostructures show very high degree of purity and uniformity. In other words, because of remarkable antioxidant properties of cochineal, it prevents silver nanoparticles from sintering and oxidizing. The silver–alumina nanocomposite were evaluated as photocatalyst for the Rhodamine B degradation using visible light irradiation and showed significant photocatalytic efficiency.