Preparation of Highly Stable and Effective N-Doped TiO₂@SiO₂ Aerogel Catalyst for Degradation of Organic Pollutants by Visible Light Catalysis

Abstract

To obtain high stable and effective TiO2 photocatalyst, nano-N-doped TiO2@SiO2 (TiO2−xNx@SiO2, 0 ≤ x ≤ 2) composite aerogels were synthesized by the sol-gel method combined with supercritical drying and direct oxidation process. The adsorption/photocatalytic degradation efficiency of TiO2−xNx@SiO2 aerogels was evaluated by the degradation of RhB in aqueous solution under visible light irradiation. The physiochemical properties of the aerogels were examined by XRD, FT-IR, TEM, SEM, TG/DTA, and BET methods. It was found that the specific surface areas of all TiO2−xNx@SiO2 samples exceeded 700 m2/g and exhibited a honeycomb porous structure with fine particulate morphology. Photocatalytic activity tests show that the 500-TiO2@SiO2 composite aerogel exhibits the best adsorption/photocatalytic degradation rate for RhB, which obtained about 80% of the degradation rate in 30 min under visible light and over 95% after 120 min. On the one hand, the SiO2 aerogels can significantly inhibit the phase transition of TiO2, and the nano TiO2 can be highly dispersed in the SiO2 aerogels; On the other hand, if the oxidation temperature is selected properly, the N-doped TiO2−xNx@SiO2 aerogel can be obtained by simple TiN@SiO2 aerogel oxidation.

Cu2+ doped TiO2–SiO2 with photonic crystal structure for synergistic enhancement of photocatalytic degradation under visible light irradiation

“…For pure TiO 2 , a broad and intense absorption peak appearing in the range of 400-700 cm −1 assigned to the stretching vibration of Ti-O-Ti bonds and Ti-O bonds [55,56]. In SiO 2 , a characteristic peak appears at 1084 cm −1 , corresponding to the asymmetric stretching vibrations of Si-O-Si [57]. All characteristic peaks of TiO 2 -SiO 2 are derived from both TiO 2 and SiO 2 samples.…”

Structural Diversity in Cryoaerogel Synthesis

“…Recently, those materials gained high interest in applications such as in catalyzed syntheses 1 , 2 as well as in electrocatalytic 3 − 5 and photocatalytic reactions. 6 , 7 Furthermore, a variety of sensing applications were reported. 8 − 10 Owing to the good accessibility of the surface, thin films or coatings from these materials experience an increasing interest.…”

“…Because of their unique physical properties such as high specific surface areas and open-pore structures, aerogels are highly investigated. Recently, those materials gained high interest in applications such as in catalyzed syntheses , as well as in electrocatalytic − and photocatalytic reactions. , Furthermore, a variety of sensing applications were reported. − Owing to the good accessibility of the surface, thin films or coatings from these materials experience an increasing interest. − In most cases, the aerogel coating is prepared by dropcasting and drying a slurry consisting of an aerogel material, solvents, and a binding substance like Nafion. − Because of mixing the slurry, however, the monolithic network is broken into smaller segments. In the resulting coating, these parts are later covered and connected using the binder.…”