Synthesis and visible-light-induced catalytic activity of Ag ₂S-coupled TiO₂ nanoparticles and nanowires

We present the synthesis and visible-light-induced catalytic activity of Ag₂S-coupled TiO₂ nanoparticles (NPs) and TiO₂ nanowires (NWs). Through a simple wet chemical process from a mixture of peroxo titanic acid (PTA) solution, thiourea and AgAc, a composite of Ag₂S NPs and TiO₂ NPs with sizes of less than 7nm was formed. When the NP composite was further treated with NaOH solution followed by annealing at ambient conditions, a new nanocomposite material comprising Ag₂S NPs on TiO₂ NWs was created. Due to the coupling with such a low bandgap material as Ag₂S, the TiO₂ nanocomposites could have a visible-light absorption capability much higher than that of pure TiO ₂. As a result, the synthesized Ag₂S/TiO₂ nanocomposites exhibited much higher catalytic efficiency for the decomposition of methyl orange than commercial TiO₂ (Degussa P25, Germany) under visible light.