石墨/TiO2复合光催化剂的制备和性能

以石墨和纯的TiO₂为原料，采用球磨工艺制备了石墨/TiO₂复合光催化剂。使用XRD、SEM、TEM、XPS和DRS等手段对其性能进行了表征。以甲基橙为模拟污染物，研究了石墨掺入量、球磨时间对复合光催化剂光催化活性的影响。结果表明，石墨/TiO₂复合光催化剂具有锐钛矿结构，球磨后TiO₂(101)面的衍射峰宽化并右移，TiO₂成为200 nm左右的不规则球状颗粒，在其表面均匀分布着石墨。TiO₂晶粒的Ti-O键的结合能变高，且表面有缺陷产生，使其在可见光区具有显著的吸收。石墨掺入量为5%、球磨时间为12 h的石墨/TiO₂样品对甲基橙具有优异的光催化降解效果，在70 min的降解时间内甲基橙的降解去除率可达95.08%。石墨/TiO₂复合光催化剂的光催化反应速率常数k为0.043035 min^-1，是纯TiO₂的2.64倍。

Preparation and Performance of Graphite/TiO2 Composite Photocatalyst

The composite photocatalyst of graphite/TiO₂ was prepared by high-energy ball milling with graphite and pure TiO₂ as the raw materials. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet diffuse reflectance (DRS). The effect of graphite addition and ball milling time on the photocatalytic activity of the prepared composite photocatalyst was investigated by comparison of their degradation efficiencies for the methyl orange as the simulated pollutant. The results show that after ball milling the graphite/TiO₂ composite photocatalyst presents an anatase-like X-ray diffraction pattern, the diffraction peak of TiO₂(101) plane widened and shifted to the right, the TiO₂ particles are irregular spherical around 200 nm, and the graphite uniformly distributed on the TiO₂ surface. Because of higher binding energy of TiO₂ grains, the defects generated on the surface of the graphite doped TiO₂ have significant absorption capacity in the visible light region. The graphite/TiO₂ composite photocatalyst with 5 mass% graphite prepared by ball milling for 12 h showed the best photocatalytic degradation effect of methyl orange. After the degradation time of 70 min the degradation removal rate of methyl orange could reach 95.08%, and the reaction rate constant k was 0.043035 min^-1, which was 2.64 times that of the pure TiO₂.