A New Synthetic Strategy of Ag-TiO2 Nanocomposites Based on Ligand-to-Metal Charge Transfer under Visible Light Irradiation: Characterizations and Photocatalytic Activity

Ag-TiO2 nanocomposites are green-synthesized by photodeposition based on ligand-to-metal charge transfer (LMCT) for the first time. Ag+ is photoreduced into Ag nanoparticles under visible light irradiation and precipitated on the surface of TiO2 (P25) nanoparticles. The physicochemical properties of as-synthesized nanocomposites are characterized by high-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet (UV)-visible diffuse reflection spectroscopy, and photoluminescence spectroscopy. The photocatalytic activity of Ag-TiO2 is evaluated by the photodegradation of methyl orange (MO) under UV light irradiation. 5.0wt% Ag-P25 nanocomposite exhibited the highest photocatalytic activity, mainly owing to the lowest recombination rate of photogenerated charge carriers. Addition of different scavengers proved that photogenerated electrons and contributed to the photocatalytic decolorization of MO. The as-prepared Ag-P25 nanocomposites had better photocatalytic ability than that of bare P25. Thus, the LMCT-sensitization-induced visible light reduction method is helpful for the green synthesis of photocatalytic nanomaterials and potentially applicable to pollutant remediation.