CdS量子点修饰TiO_(2)纳米管及光解水产氢性能研究

TiO_(2) Nanotubes Modified by CdS Quantum Dots and Performance of Photocatalytic Water Splitting for Hydrogen

二氧化钛(TiO_(2))是一种传统的光催化剂材料,但由于其自身带隙宽(3.2 eV)及光生载流子易复合,往往需要通过贵金属或过渡金属掺杂、阴离子掺杂、构建异质结等手段增强其对太阳光的有效吸收,促使光生载流子分离并抑制其复合。采用两步法构建TiO_(2)/CdS异质结,首先通过多重电压阳极氧化法制备结构化的TiO_(2)纳米管阵列,再以TiO_(2)纳米管为基底,通过化学浴沉积法在TiO_(2)纳米管管壁内外均匀生长CdS量子点。通过X射线衍射、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)和紫外‐可见光谱(UV‐VIS)对TiO_(2)/CdS异质结组成、形貌和光学性质进行了表征。结果表明,构建的TiO_(2)‐CdS异质结有效抑制光生载流子复合,促进激发电子的转移,提高光催化产氢效率;样品TiO_(2)(1.0)‐CdS(1.0)产氢效率达到1.30 mmol/(g⋅h),是CdS量子点的1.67倍。最后,基于实验分析提出了可见光光解水制氢过程中光生电子在TiO_(2)-CdS上的转移机制。

Titanium dioxide(TiO2)is a traditional photocatalyst material.However,due to its wide band gap(3.2 eV)and the easy recombination of photogenerated carriers,it is necessary to enhance the effective absorption of sunlight,promote the separation of photogenerated carriers,and inhibit their recombination by doping noble metals,transition metals,anions and constructing heterojunctions.TiO_(2)/CdS heterojunctions were prepared in two steps.Firstly,TiO_(2) nanotube arrays were prepared by multiple voltage anodization.Then,with TiO_(2) nanotubes as the base,CdS quantum dots were uniformly deposited inside and outside the nanotubes through chemical bath deposition.The composition,morphology,and optical properties of TiO_(2)/CdS heterojunctions were characterized by X‐ray diffraction,scanning electron microscopy(SEM),transmission electron microscopy(TEM),X‐ray photoelectron spectroscopy(XPS),and UV‐visible spectroscopy(UV‐VIS).The prepared TiO_(2)/CdS heterojunctions effectively inhibited the recombination of photogenerated carriers,promoted the transfer of excited electrons,and improved the hydrogen production efficiency by photocatalysis.The hydrogen production efficiency of sample TiO_(2)(1.0)‐CdS(1.0)reached 1.30 mmol/(g⋅h),which was 1.67 times that of CdS quantum dots.Finally,according to the experimental analysis,the transfer mechanism of photogenerated electrons on TiO_(2)/CdS during photocatalytic water splitting for hydrogen was proposed.