ABSTRACT
Ag/TiO2/muscovite (ATM) composites were prepared by the sol-gel method and the effects of Ag modification on the structure and photocatalytic performance were investigated. The photocatalysts were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller surface area (BET), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (FTIR), photoluminescence spectra (PL) and ultraviolet-visible diffuse reflectance spectra (DRS). The photocatalytic activity of the obtained composites was evaluated by taking 100 mL (10 mg/L) of Rhodamine B (RhB) aqueous solution as the target pollutant. The muscovite (Mus) loading releases the agglomeration of TiO2 particles and the specific surface area increases from 17.6 m2/g (pure TiO2) to 39.5 m2/g (TiO2/Mus). The first-order reaction rate constant increases from 0.0009 min-1 (pure TiO2) to 0.0074 min-1 (150%TiO2/Mus). Ag element exists in elemental silver. The specific surface area of 1-ATM further increases to 66.5 m2/g. Ag modification promotes the separation of photogenerated electrons and holes and increases the visible light absorption. 1%Ag-TiO2/Mus (1-ATM) exhibits the highest photocatalytic activity. After 100 min, the rhodamine B (RhB) degradation degrees of PT, 150%TiO2/Mus and 1-ATM are 10.4%, 48.6% and 90.6%, respectively. The first-order reaction rate constant of 1-ATM reaches 0.0225 min-1, which is 25 times higher than that of pure TiO2.
ABSTRACT
With zinc acetate and butyl titanate as raw materials, pure ZnO and ZnTiO3/ZnO composite photocatalysts were synthesized by a sol-gel method and calcined at 550 °C. The crystal structure, morphology, surface area, optical property, and element valence states of samples were characterized and the photocatalytic activity of the prepared photocatalysts were assessed by the degradation of rhodamine B. Results show that the crystal structure of ZnO is a hexagonal wurtzite phase with a band gap of 3.20 eV. When the Zn/Ti molar ratio reaches 0.2, ZnTiO3 phase appears and ZnTiO3/ZnO composite forms, which advances the transfer of photogenerated charges. ZnTiO3/ZnO (Ti/Zn = 0.2) exhibits the highest photocatalytic activity, and the degradation degree of RhB reaches 99% after 60 min, which is higher than that of pure ZnO (90%). An exorbitant Ti/Zn molar ratio will reduce the crystallinity and form more amorphous components, which is not conducive to photocatalytic performance. Therefore, when the Ti/Zn molar ratio exceeds 0.2, the photocatalytic activities of ZnTiO3/ZnO composites decrease.
ABSTRACT
The anatase/rutile mixed crystal TiO2 was prepared and modified with Ag decoration and SnO2 coupling to construct a Ag@SnO2/anatase/rutile composite photocatalytic material. The crystal structure, morphology, element valence, optical properties and surface area were characterized, and the effects of Ag decoration and SnO2 coupling on the structure and photocatalytic properties of TiO2 were studied. Ag decoration and SnO2 coupling are beneficial to reduce the recombination of photogenerated electrons and holes. When the two modification are combined, a synergistic effect is produced in suppressing the photogenerated charge recombination, making Ag@SnO2/TiO2 exhibits the highest quantum utilization. After 30 min of illumination, the degradation degree of tetracycline hydrochloride (TC) by pure TiO2 increased from 63.3% to 83.1% with Ag@SnO2/TiO2.
