Chen Yanmo

Preparation of LaTiO2N photocatalyst with a large surface area

In this following communication, a new nanocrystalline photocatalyst LaTiO2N with a large surface area of 27.5 m2/g was synthesized by nitridation of amorphous La2O3/TiO2 composite powder at 900°C for 8 h using NH3 as the reactant gas, and the co-precipitate method was used to synthesize the high active amorphous La2O3/TiO2 composite powder. The X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) results revealed that the as-prepared LaTiO2N nanocrystals had a mean diameter of about 30 nm. With increasing the nitrided temperature from 700°C to 900°C, it can be seen that the color of the oxynitride vary from yellow to red, and the specific surface area of the sample became lower since the high temperature can lead to the coalescence and aggregation of the nanoparticles. Both a higher nitridation temperature and a longer nitridation time can lead to a higher nitrogen content of the oxynitride. The TEM of the oxynitride obtained at 700°C, 800°C revealed some voids are in the oxynitride nanoparticles, which may be attribute to the density difference between oxide and oxynitride. The band gap energy of LaTiO2N was estimated to be 2.1 eV for its absorption band was founded to extend to 600 nm, it indicated that the synthesized oxynitrides displayed good light absorption properties not only in the ultraviolet light but also in the visible light region. Its high specific surface area and narrow band gap energy may guarantee photocatalytic activity under visible light excitation.