环取代基对金属化聚苯胺衍生物膜修饰电极性能的影响

Effects of Ring-substituted Groups on the Properties of Metallized Polyaniline Membrane Modified Electrode

通过比较聚 2 ,5 -二甲氧基苯胺 (PDMAn)、聚邻甲基苯胺 (POT)和聚间氯苯胺 (Pm Cl An)膜修饰电极的氧化还原电位、沉积在这 3种聚合物上的铂微粒的表面形态与晶面取向以及异丙醇在分散 Pt微粒的聚苯胺膜修饰电极上的氧化行为 ,从电子效应和立体效应探讨了聚合物电化学性质与环取代基的关系以及不同聚合物基质对 Pt沉积机理和电极催化性能的影响 .结果表明 ,在硫酸溶液中 PDMAn膜修饰电极的氧化还原电位最负、 POT次之、 Pm Cl An最正 .Pt在 PDMAn和 POT膜上的电沉积机理与在 Pm Cl An膜上的不同 ,聚合物膜上沉积的 Pt微粒呈现 (2 0 0 )晶面择优取向 ,其中 POT膜上择优取向度最大 ,PDMAn次之 ,Pm Cl An最小 .异丙醇在金属化聚合物膜电极上的氧化电位取决于聚苯胺的本质 ,在 POT膜修饰电极上异丙醇的电氧化主要发生在 POT的活性电位区 ,而在 PDMAn与 Pm Cl An膜上的电氧化则主要发生在 Pt上的氧化电位区 ,说明聚合物膜不仅作为 Pt微粒的分散介质 ,而且本身可能产生催化作用 .

By comparing the redox potentials of poly 2,5 dimethoxyaniline(PDMAn), poly o toluidine(POT) and poly m chloroaniline(PmClAn) membrane modified electrodes, the morphology and crystal face orientation of Pt deposited on these polymers and isopropanol oxidation behavior on the platinized polyaniline electrodes, the relation of electrochemical properties of polyanilines to ring substituted groups in the polymers and the influence of different polyaniline on Pt deposition and the catalytic properties of platinized polyaniline modified electrodes were discussed in terms of the electronic and steric effects. The results indicated that among 3 polyanilines, the redx potential of PDMAn was the most negative, and that of POT was less negative, and that of PmClAn was the most positive. The electrodeposition mechanisms of Pt particles on POT and on PDMAn membranes were different from that on PmClAn membrane. The Pt particles deposited on polyanilines were inclined towards the preferred orientation of Pt(200) crystal face, but the degree of preferred orientation depended on polymers. The preferred orientation on POT was stronger than that on PDMAn, and the weakest on PmClAn. The potentials of isopropanol oxidation on platinized polyaniline modified electrodes rely on the nature of polyanilines matrix. On POT modified electrode the isopropanol oxidation mainly occurs in the potential region where POT is electroactive, but on PDMAn and PmClAn modified electrodes it takes place in the potential region same as that on Pt. It follows that polymer matrix was not only as disperse media of Pt particles, but also exerts catalytic actions.