C-N共掺杂纳米TiO2的制备及其光催化制氢活性

采用TiCN粉末在空气气氛中不同温度下焙烧制得C-N共掺杂的纳米TiO2光催化剂. 利用X射线衍射(XRD)、透射电镜(TEM)、紫外-可见漫反射光谱(UV-Vis DRS)以及X射线光电子能谱(XPS)等手段对其进行了表征. XRD和XPS结果表明, TiCN中的C和N元素可以被O取代得到C-N共掺杂的TiO2. DRS结果表明, 所制得的C-N共掺杂的TiO2在可见光区域比P25表现出更强的光吸收性能. 以Na2S-Na2SO3体系为牺牲剂, 分别考察了不同温度下焙烧得到的C-N共掺杂的TiO2光催化分解水产氢的活性. 结果表明, 550 ℃焙烧得到的C-N共掺杂的TiO2在紫外光照射下具有最高的光解水产氢活性,产氢速率为41.1 μmol·h-1, 大于P25的光解水产氢活性(26.2 μmol·h-1). 在紫外-可见光照射下, 光解水产氢速率仅为0.2 μmol·h-1, 这可能是由于C-N掺杂引起的可见光范围的吸收对光催化分解水产氢活性的贡献较小.

Preparation and Photocatalytic Hydrogen Evolution Performance of C-N Co-doped Nano TiO2 Photocatalysts

Carbon-nitrogen co-doped titanium dioxide (TiO2) nanoparticles were synthesized by calcining titanium carbonitride (TiCN) powder in air at different temperatures. The as-prepared powders were characterized by X-ray diffraction (XRD), transmission electron microscopy(TEM), ultraviolet-visible diffuse reflectance spectroscopy(UV-Vis DRS), and X-ray photoelectron spectroscopy (XPS). XRDand XPS results showed that nitrogen and carbon in the TiCN lattice could be replaced by oxygen through calcining the TiCN powder in air. Stronger light absorption in both the UV and visible light region was observed for the as-prepared powders compared to commercial P25 from the DRS results. The photocatalytic hydrogen evolution performance over both the as-prepared catalysts and P25 was tested using Na2S-Na2SO3 as a sacrificial electron donor under UV and UV-Vis light irradiation. The highest photocatalytic activity was observed for CN-TiO2 obtained fromTiCNand calcined at 550 ℃. The hydrogen evolution rate reached 41.1 μmol·h-1, which is higher than that from P25 (26.2 μmol·h-1). This may be caused by a synergistic effect between doped C and N elements. Under UV-Vis light illumination, the highest hydrogen evolution rate was 0.2 μmol·h-1, which may be due to a minor contribution of visible light absorption to water photo-splitting for hydrogen production.