A New Synthetic Strategy of Ag-TiO_2 Nanocomposites Based on Ligand-to-Metal Charge Transfer under Visible Light Irradiation: Characterizations and Photocatalytic Activity

摘要

Ag-TiO_2 nanocomposites are green-synthesized by photodeposition based onrnligand-to-metal charge transfer (LMCT) for the first time. Agþ is photoreducedrninto Ag nanoparticles under visible light irradiation and precipitatedrnon the surface of TiO_2 (P25) nanoparticles. The physicochemical properties ofrnas-synthesized nanocomposites are characterized by high-resolution transmissionrnelectron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy,rnultraviolet (UV)-visible diffuse reflection spectroscopy, and photoluminescencernspectroscopy. The photocatalytic activity of Ag-TiO_2 is evaluated by thernphotodegradation of methyl orange (MO) under UV light irradiation. 5.0 wt%rnAg-P25 nanocomposite exhibited the highest photocatalytic activity, mainlyrnowing to the lowest recombination rate of photogenerated charge carriers.rnAddition of different scavengers proved that photogenerated electrons andrn•O_2~- contributed to the photocatalytic decolorization of MO. The as-preparedrnAg-P25 nanocomposites had better photocatalytic ability than that of barernP25. Thus, the LMCT-sensitization-induced visible light reduction method isrnhelpful for the green synthesis of photocatalytic nanomaterials and potentiallyrnapplicable to pollutant remediation.