微波法制备CdS-TiO_2NT复合催化剂及其在可见光下分解水制氢的性能

Preparation of CdS-TiO2NT Composite Catalysts by Microwave Irradiation Method and its Phtocatalytic Performance of Splitting Water to H_2 under Visible Light

以CdCl2·2.5H2O,Na2S·9H2O和自制的TiO2纳米颗粒为原料,在微波反应器内合成了掺杂CdS的TiO2纳米管复合催化剂。通过高分辨透射电镜观察,发现采用此方法可合成形貌完好纳米管,管子内径为5-10nm,长度为150-200nm。X射线衍射表征结果显示合成的复合催化剂主要为锐钛矿型的多晶态TiO2纳米管,并且CdS的掺杂造成TiO2晶体变形,可能是CdS与TiO2之间存在相互作用和CdS部分进入TiO2晶格内部。X射线光电子能谱对该催化剂各元素电子环境进行了分析。紫外可见吸收光谱发现所制备的复合催化剂产生明显的红移现象,能吸收可见光。该催化剂在可见光下催化分解纯水制氢的催化性能结果表明,掺杂CdS（1.96%（wt））的TiO2纳米管催化剂能分解纯水产生氢气,产氢速率为12.9μmol·（h·g）^-1,而纯CdS纳米颗粒、纯TiO2纳米管以及这两者物理混合的催化剂则检测不到氢气的产生。通过考察不同CdS的掺杂量,发现CdS质量分数为1.96%的CdS-TiO2NT催化剂的可见光下催化活性最好。

Using CdCl2·2.5 H2O, Na2S·9H2O and TiO2 as raw materials, the CdS-TiO2NT composite catalysts with photocatalytic ability were prepared by microwave irradiation method. The results of XRD spectra indicate that the prepared CdS-TiO2NT catalysts are mainly consisted of TiO2 multicrystal nanotubes with anatase phase, and the doping of CdS deforms the TiO2 crystal probably due to the interaction between CdS and TiO2. Through high resolution TEM images, it was found that the prepared TiO2 nanotubes with CdS have inner diameter of 5~10 nm and length of 150~200 nm. XPS spectra were also adopted to analyze the electron environment of the elements in the prepared catalysts. The results of UV-vis absorbance spectra indicate that the prepared CdS-TiO2NT have obvious red shift and could absorb visible light. The experiments of catalytic splitting water to hydrogen show that, under the visible light, the hydrogen evolution rate of 1.96CdS-TiO2NT composite catalyst could be 12.9 μmol·（h·g）-1. However, using the mixed CdS＋ TiO2 nanotube, pure TiO2 nanotube and only CdS as catalyst, respectively, no H2 evolution from water under visible light can be detected. It was also found that, among a series of the photocatalysts CdS-TiO2NT with different CdS contents, the CdS-TiO2NT with CdS mass fraction of 1.96%—1.96CdS-TiO2 nanotube catalyst has the best photocatalytic activity under visible light.