离子液体中纳米TiO2/聚3-甲基噻吩复合膜的制备及性质研究

采用溶胶凝胶法制成了纳米TiO₂电极, 在离子液体中将其应用于3-甲基噻吩的电化学聚合, 采用循环伏安法(CV), 在线紫外可见光谱(UV-Vis), 扫描电镜(SEM)和电化学阻抗谱(EIS)对TiO₂/聚3-甲基噻吩(TiO₂/PMT)复合膜进行了表征并研究了其电化学性质. 实验证明, 不论是用循环伏安法, 恒电位, 还是恒电流方法, 都能在电极上得到聚3-甲基噻吩(PMT)膜, 并伴随有明显的掺杂和去掺杂过程. 对应的在线紫外可见光谱上, 也出现了氧化和还原两种不同的吸收状态, 还原(去掺杂)过程中在480 nm处有一个吸收峰, 而氧化(掺杂)过程中此峰消失, 取而代之的是一个可见光区的逐渐增强的吸收. PMT膜是p型半导体, TiO₂是n型半导体, 两者之间能够形成p-n异质结, 使光电转换效率得以提高. SEM给出了TiO₂电极和聚合物修饰的TiO₂的形貌图, 电极的交流阻抗谱则从一个角度说明了聚合物膜修饰电极的导电性.

Preparation and Property Study of Nano-TiO2/3-Methylthiophene Composite Film in Ionic Liquid

Nano-TiO₂ electrode was prepared by sol-gel method, and then applied the electrode to the electropolymerization of 3-methylthiophene. The properties of the composite film were studied by cyclic voltammetry (CV), UV-vis absorption spectra, scanning electron micrographs (SEM) and electrochemical impedance spectrum. Poly(3-methylthiophene) (PMT) film was obtained successfully and showed obvious doping and dedoping process. The in situ UV-vis spectra showed the transition peaks of oxidation and reduction states. In the reduction (dedoping) process, the electrode exhibited an absorption peak at 480 nm, while the peak disappeared in the oxidation (doping) process, replaced by an increasing visible light absorption. The p-n heterojunction existed in the nano-TiO₂/PMT film electrode, which can improve the photon-electron conversion efficiency. The EIS spectrum presents the conductivity of the composite film.