Facile approach for homogeneous dispersion of metallic silver nanoparticles on the surface of mesoporous titania for photocatalytic degradation of methylene blue and indigo carmine dyes

摘要

Homogeneous incorporation of an appropriate amount of metallic Ag nanoparticles on titania surface is essential parameter in optimizing the photocatalytic reactivity and stability of the photocatalyst. In this current research, metallic silver nanoparticles decorated titania were synthesized by sol-gel route using chitosan as nano-assembling template and reducing agent. The physicochemical features were investigated by X-ray diffraction [XRD], N-2-adorption-desorption isotherm, Energy dispersive X-ray [EDX], diffuse reflectance spectra (DRS), Photoluminescence IPLI, Field emission Scanning emission electron microscope [FESEM] and High resolution transmission electron microscope. Three prevailing diffraction peaks in XRD analysis assigned to metallic silver nanoparticles was observed confirming the successful role of chitosan in reducing silver ions. Various pores of different sizes ranging from supermicropores to wide mesoporous structure are created due to deposition of Ag particles on titania pore mouth. Benefiting from the uniform dispersion of Ag nanoparticles, the Ag/TiO2 nanohybrids show favorable reactivity in the photodegradation of methylene blue and indigo carmine dye as cationic and anionic pollutant models. This enhanced photocatalytic reactivity arise from the positive synergetic effects of the metallic silver nanoparticles and titania including an electron transfer from titania conduction band to fermi level of metallic silver nanoparticles and reduction in electron -hole recombination. This novel research work will open a new doorway to prepare highly photoactive mesoporous Ag/TiO2 nanoparticles without using an external reducing agent. (C) 2016 Elsevier B.V. All rights reserved.