煅烧氛围对N-TiO2可见光催化性能的影响

Effect of calcination atmospheres on visible light photocatalytic performance of N-TiO2

以钛酸丁酯为钛源,以尿素为氮源,采用溶胶-凝胶法制备TiO2中间体,分别在空气和氮气氛围下煅烧制得N-TiO2光催化剂,采用XRD、TEM、BET、UV-vis DRS、FT-IR、EDS和XPS等手段进行表征,以甲基橙溶液为目标污染物考察了其可见光催化性能。结果表明:N-TiO2(N2)较N-TiO2(空气)具有晶粒尺寸小、可见光响应性强和有效掺氮量高等优势;可见光持续光照240 min时,N-TiO2(N2)对甲基橙溶液的光降解率达86.2%,较N-TiO2(空气)提高近20%;N-TiO2对MO的可见光降解反应符合假一级动力学方程,且N-TiO2(N2)的表观速率常数是N-TiO2(空气)的近5倍。N-TiO2制备过程中采用N2氛围下煅烧处理较空气氛围更有利于N元素的有效掺入,相应地,可见光催化活性更高。

The intermediate N-doped TiO2 was firstly prepared by sol-gel method using butyl titanate as titanium source and urea as nitrogen source, then was calcined in air and nitrogen atmosphere, respectively, N-TiO2 photocatalysts were produced accordingly. XRD, TEM, BET, UV-vis DRS, FT-IR, EDS and XPS were used to characterize them, and their visible-light catalytic activities were investigated when methyl orange(MO)solution was selected as the model pollutant. The results showed that compared with N-TiO2(air), N-TiO2(N2)had smaller grain size, stronger visible-light response, higher effective nitrogen doping and so on. When visiblelight irradiated for 240 min, the photodegradation rate of MO with N-TiO2(N2) was up to 86.2 %, which was about 20 % higher than that of N-TiO2(air). The visible-light degradation reaction of MO with N-TiO2 fitted pseudo-first-order kinetic equation, and the apparent reaction rate constant of N-TiO2(N2) was 5 times as large as that of N-TiO2(air). So the calcination of N-TiO2 in N2 atmosphere was more favorable to the effective doping of N element than that of air atmosphere. Correspondingly, the visible light catalytic activity of N-TiO2(N2) was higher than that of N-TiO2(air).