SiO2负载氮掺杂TiO2可见光响应光催化剂的制备及性能

以四氯化钛为钛源,尿素为氮源,采用液相水解-沉淀法制得SiO2负载N掺杂TiO2可见光响应TiO2-xNy/SiO2光催化剂(TSN)。以苯酚为模型物,考察了TSN在可见光区、紫外光区及太阳光下的光催化活性,以及催化剂的使用寿命、分离性能。采用XPS、FTIR、UV-Vis DRS、XRD、TEM和低温氮物理吸附等对催化剂的结构进行表征。结果表明,N以阴离子形式进入TiO2体相并置换晶格中的O,适量N掺杂的TSN在紫外光区、可见光区及太阳光下均表现出较高的活性。SiO2与TiO2界面间有Ti-O-Si键形成,结合牢固。N掺杂在TiO2表面生成Ti-O-N键,形成新的能级结构,使催化剂的吸收红移至450~500 nm,诱发TiO2可见光催化活性。SiO2负载可减小TiO2颗粒平均尺寸,增加催化剂比表面积;同时SiO2负载还可改善催化剂的分离性能,提高催化剂使用寿命。

Preparation and Properties of SiO2 Supported Nitrogen-Doped Visible-Light Response TiO2-xNy/SiO2 Photocatalysts

Nitrogen-doped TiO₂ photocatalysts supported on SiO₂ (TSN) with Visible-light response were prepared by a hydrolysis-precipitation method. The photocatalytic activity of the title catalyst was investigated using the photocatalytic degradation of phenol as a model reaction. The separability of TSN was determined by gravity sedimentation. The catalyst was characterized by XPS, FTIR, UV-Vis DRS, XRD, TEM and N₂ adsorption isotherm. The results show that the anion N is incorporated into TiO₂ lattice and substitutes part of O. TSN with suitable N-doping exhibits high activity under ultraviolet light, artificial visible light and solar irradiation. TSN exhibits better decantability and less deactivation. Doping of N can form a new bond of Ti-O-N resulting in a new band gap above the valence band of TiO₂ to extend the adsorption edge to 450~500 nm. Also, SiO₂ is beneficial to the higher dispersion and larger surface area of TSN.