Preparation And Visible-Light Photocatalytic Activity Of N-TiO₂/Foam Ceramic

In this paper,nitrogen-doped TiO2（N-TiO2）was prepared using urea as the nitrogen source,and characterized by XRD,TEM,UV-Vis,XPS and other characterization methods,and its visible-light catalytic performance was investigated.N-TiO₂/foam ceramicl was prepared by loading N-TiO₂ on the foam ceramic in gluing method and were characterized by BET and SEM,and its visible-light catalytic performance was investigated.The results were as follows.1)N-TiO₂ was prepared by sol-gel method and high-temperature calcination process（in nitrogen atmosphere）using urea as nitrogen source.The optimum preparation conditions were 3:1 of N:Ti mole ratio,2 h of calcination time and 450°C of calcination temperature.The crystal form was anatase phase with the grain size of about 5-7 nm,its specific surface area of 74.643 m²·g^-1,the average pore diameter of 3.413 nm,and the total pore volume of 0.083 cc·g^-1.The band gap energy of N-TiO₂ was 1.6 eV,and compared with pure TiO₂,the absorption band was significantly red-shifted,showing good visible-light response.The doping forms of nitrogen were interstitial-N and alternative-N.For both methyl orange solution and acetone gas,the N-TiO₂ photocatalyst had good visible-light catalytic activity and good cyclical stability.2)The open-cell foam ceramics made of silicon carbide was used as the carrier of the photocatalyst.Its pore density was 22,the bulk density was 0.62 g·cm^-3,the porosity was77.2%and the number of thermal shock resistance cycles was 5 times.The foam ceramic had rich mesopores,and its pore size mainly distributed between 2⁴ nm and 4.5⁸ nm.It had a special pore structure on the surface and the diameter was between 0.1μm and 1μm.3)N-TiO₂/foam ceramic composite photocatalytic material was effectively prepared by loading N-TiO₂ on the foam ceramic in gluing method.It had 11.012 m²·g^-1 of specific surface area,0.014 cc·g^-1 of total pore volume and 3.777 nm of average pore diamete.For acetone gas,the N-TiO₂/foam ceramic composite prepared by 3-time repeatition had the best visible-light degradation effect.The higher the light intensity was,the higher the photodegradation rate of acetone was.Compared with the low-concentration acetone gas,the high-concentration acetone had a higher photodegradation rate at the initial stage of the reaction,while the photodegradation rate became smaller in the middle and late stages of the reaction.Although if acetone gas concentration was too high,the deactivation rate of the N-TiO₂/foam ceramic composite would be accelerated,so the photodegradation rate of acetone gas would decrease.