Photoreduction synthesis of silver on Bi2O3/TiO2 nanocomposites and their catalytic activity for the degradation of methyl orange

This paper demonstrates the preparation of pure TiO2, 40% of Bi2O3 in TiO2 and Ag loaded Bi2O3/TiO2 nanocomposites by the hydrothermal method followed by the photoreduction process. The crystal structure, morphology and composition of the samples were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy respectively. The dispersion of Ag nanoparticles on the surface of Bi2O3/TiO2 nanocomposites are found to bring the conduction band near to the valence band, resulting in the narrow band gap compared to pure TiO2 and Bi2O3/TiO2 nanocomposites. The XRD analysis demonstrated that silver nanoparticles were dispersed finely on the surface of Bi2O3/TiO2 nanocomposites. All the characterization results revealed that the Ag/Bi2O3/TiO2 nanocomposites were smaller crystallite size, stronger absorbance in the visible region and greater surface area than pure TiO2 and Bi2O3/TiO2 nanocomposites. The photoluminescence intensity decreases with an increase in the UV-illumination time of Ag loaded Bi2O3/TiO2 revealing a decrease in the recombination rate of electron–hole pairs. In order to test them as a photocatalyst, methyl orange was used as a standard. The photocatalytic degradation of methyl orange shows that the ABT5 sample exhibits the maximum degradation efficiency of 99% within 180 min of irradiation.