Ag nanoparticle-impregnated sulfonated graphene/TiO2 composite for the photocatalytic removal of organic pollutants

In this study, highly dispersed Ag and TiO2 nanoparticles decorated sulfonated graphene nanosheets (SGTAg) were synthesized and demonstrated to be an efficient photocatalyst for the degradation of aqueous cationic dye Rh.B, anionic dye MO and 4-NP under sunlight. Pursuance of photocatalytic degradation of these recalcitrant organic pollutants over wide pH range shows the catalysts universally degrade all pollutants over 98% in the pH range of 3-7. The reaction kinetics of SGTAg found to be 4-9 fold higher photocatalytic activity than that of pristine TiO2. Analysis of products of photocatalysis by ESI-MS confirms the degradation of Rh.B and MO. Detail spectroscopic characterization of photocatalyst has been carried out by XRD, UV-vis, PL, FTIR, Raman, FE-SEM, XPS, and HR-TEM. It is inferred that the enhanced photocatalytic efficiency of nanocomposites in this material originates from extended light absorption ability in the visible region, effective electron transport ability rendered by Ag loaded sulfonated graphene nanojunction and interfacial electron transfer in the sulfonated graphene nanosheets, as illustrated by UV-Vis and PL emission studies. Further, the results find SGTAg composite to be highly stable and could be reused for many cycles without significant deterioration of its catalytic activity.