导电聚合物-半导体纳米颗粒自组装膜(Ⅱ)——光电化学性质

Nanocomposite Films of Conductive Polymer/SemiconductorNanoparticles(Ⅱ)- Photoelectrochemical Properties

研究了层层自组装技术制备的导电聚合物ＳＰＡｎ/纳米硫化镉复合膜的电化学和光电化学性质．单层ＳＰＡｎ膜在０．１ｍｏｌ/Ｌ的ＬｉＣｌＯ４/乙腈电解液中有弱的阴极光电流效应,为ｐ型半导体;化学沉淀ＣｄＳ膜为ｎ型半导体．复合膜ＰＳＳ/Ｑ－ＣｄＳ仅有阳极光电流效应,为ＣｄＳ的ｎ型半导体．自组装复合膜ＳＰＡｎ/Ｑ－ＣｄＳ有两种不同类型的光电响应,在阴极区(导电聚合物ＳＰＡｎ处于未掺杂状态)具有阴极光电流,在阳极区(ＳＰＡｎ处于导电状态)具有阳极光电流;导电聚合物的电化学状态对复合膜的光电化学性质有决定性作用．

Using layer-by-layer self-assembly techniques, we successfully constructed nanostructured mul-tilayer films of conjugated polymer (sulfonic acid ring substituted polyaniline, SPAn)/semiconductornanoparticles(Q-CdS). Cyclic voltammograms of single layer film of SPAn in 0.1mol/L Na2SO4 solution(pH=3.0) consists of two redox peaks. The electrochemical processes associated with the peaks are twosteps redox doping. The S2- in the composite films is unstable and easily oxidized to product S, S2O_3^(2-) andSO_4^(2-) as being determined by X-ray photoelectron spectroscopy. The films of the first layer SPAn exhibiteda weak photoinduced cathodic current over the potential range between O and -600 mV(vs. SCE) in 0.1mol/L LiClO4 solution in acetonitrile. The self-assembly films of SPAn/Q-CdS exhibited a photocathodicacurrent under cathodic bias and photoanodic current under anodic bias. In contract, the films of poy(sodi-um 4-styrenesolfonate)/Q-CdS only exhibited a photoinduced anodic current from - 500 to 600 mV. Itimplied that the state(doping or undoping) of the conjugated polymer play an important role in determiningthe photoelectrochemical properties of the films.