钒掺杂二氧化钛薄膜制备与材料特性分析

Preparation and characterization of V-doped titanium oxide thin films

以钛酸四丁酯和乙酰丙酮钒(Ⅲ)为主要原料,采用溶胶-凝胶法制备了钒掺杂二氧化钛薄膜,利用XRD、紫外-可见吸收光谱、FT-IR及XPS等表征手段,将其与未掺杂二氧化钛薄膜进行了材料特性对比研究。结果表明两种薄膜均为锐钛矿结构,引入钒后二氧化钛的禁带宽度由3.28eV减小至3.15eV,吸收带边红移至可见光范围;XPS分析证实制备的钒掺杂二氧化钛薄膜中钒以四价和五价两种氧化价态存在,可能在二氧化钛禁带中引入较深的杂质能级而引起价带顶向禁带拓展,从而产生引起禁带宽度变窄效应,扩展了二氧化钛带边光吸收。理论分析还表明,钒掺杂引起的深能级杂质在二氧化钛晶界处易于形成有效的陷阱俘获光生空穴,从而抑制光生载流子的复合,尤其适于用作光催化材料。

V-doped TiO2 films were prepared by sol-gel method starting from tetrabutyl titanate and vanadium（Ⅲ） 2,4-pentanedionate.Their properties were characterized by XRD,UV-Vis absorption spectra,FT-IR,and XPS with the undoped film samples as the control.Both the V-doped and undoped TiO2 films are anatase and the band gap decreases from 3.28 to 3.15eV,with a red shift in the absorption of V-doped TiO2 film compared to the undoped samples.The V-doped films consist of vanadium atoms in the V4＋ and V5＋ oxidation states,generating deep defect levels and the valence bandedge might extend into the forbidden band gap,inducing the band gap narrowing effect and enhancing the bandedge absorption.At the grain boundaries of TiO2,those impurity defects located deep inside the gap become closer to the top of the valence band and hence tend to trap the photo-generated holes,which would contribute to inhibit the recombination of photogenerated carriers and become highly attractive for application in photocatalytic materials.