Preparation and photocatalytic properties of porous C and N co-doped TiO2 deposited on brick by a fast, one-step microwave irradiation method.

A one-step microwave irradiation method was used to deposit carbon and nitrogen co-doped TiO2 ((C, N)-TiO2) on commercial brick ((C, N)-TiO2/brick). The as-prepared samples were characterized by X-ray diffraction, ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy (SEM). A selective technique was also used to investigate the concentration of hydroxyl radicals during UV-vis irradiation of the Methyl Orange solution with the as-prepared samples. The C and N dopants enhanced visible light absorption and provided a longer lifetime for the photo-generated electron-hole pairs. The SEM images showed that the as-prepared sample is porous. The dark adsorption and photodegradation test for (C, N)-TiO2/brick showed good photodegradation and good recyclability. The best photodegradation rate was 94% after 2hr. The maximum degradation rate was maintained even after the 6th cycle. The good photocatalytic properties are attributed to the enhanced visible light absorption, enhanced pollutant adsorption arising from the porous structure of the (C, N)-TiO2 thin film, and longer lifetime of the photo-generated electron-hole pairs. (C, N)-TiO2/brick should have potential commercial applications in photodegradation processes because of its low cost, good photodegradation, and excellent recyclability.