不同介质对Pt/GC电极制备及其性能的影响

应用循环伏安法(CV),扫描电子显微镜(SEM)和电化学原位红外反射光谱(in situFTIRS)研究了不同介质对碳载铂纳米薄膜电极(Pt/GC)的表面结构以及该薄膜电极对甲酸电催化氧化性能的影响.结果表明,使用不同介质的镀铂溶液,均可电沉积出分布较为均匀的Pt粒子,但其尺寸与形貌却相差很大.当以H2SO4作介质,由循环伏安法于玻碳电极上电沉积Pt得到的(Pt/GC1)电极,其Pt粒子粒径约100~200 nm;而在HClO4介质得到的(Pt/GC2)电极,则含有两种Pt微晶:其一是立方体形,粒径约200 nm,其二为菜花状,粒径约400 nm.电化学循环伏安和原位红外反射光谱测试指明,不同介质制备的Pt/GC电极对甲酸的电催化氧化均表现出与本体铂电极(Pt)相类似的特性,即可通过活性中间体或毒性中间体将甲酸氧化至CO2,但不同结构的Pt/GC电极具有不同的电催化活性.进一步以Sb或Pb修饰Pt/GC电极,不仅可以有效地抑制毒性中间体CO的生成,而且还能显著提高其电催化活性.比较本文研究的7种电极,其电催化活性顺序依次为:Sb-Pt/GC2>Pb-Pt/GC2>Pb-Pt/GC1>Sb-Pt/GC1>Pt/GC2>Pt/GC1>Pt.

Influence of Electrolyte on the Preparation and Electrocatalytic Properties of Pt/GC Electrodes

Influence of electrolyte on the electrocatalytic properties of Pt/GC electrodes for formic acid oxidation were studied by using cyclic voltammetry,SEM and electrochemical in situ FTIR spectroscopy.It has demonstrated that the surfaces of Pt/GC electrodes prepared in H2SO4 (Pt/GC1) or in HClO4(Pt/GC2) are all composed of platinum particles,but which crystals are some differences in size and shape.Diameters of platinum particles on the surface Pt/GC1 are of 100~200 nm,and with spheral shape in the majority.The sizes of platinum particles on the Pt/GC2 electrode are larger in general,part of particles is of cube shape and of diameter about 200 nm,and another part of particles is about 400 nm in diameter and of cauliflower shape.It has observed that all Pt particles are distributed relatively even on GC substrate.The results show that the electrocatalytic mechanism of formic acid oxidation on Pt/GC is similar to that on massive platinum,which involves two paths,i.e.one way through active intermediate and another through poison intermediate to CO2.It is flowed that the Pt/GC2 exhibits higher electrocatalytic activities than Pt/GC1.The electrodes ofPt/GC modified by Sb or Pb(Sb-Pt/GC or Pb-Pt/GC)are also prepared in the work.It is indicated that Sb-Pt/GC and Pb-Pt/GC enable not only to inhibit effectively the formation of poison intermediate CO,but also to increase significantly the electrocatalytic activity for oxidation of HCOOH through active intermediates.The electrocatalytic activities for seven electrodes to formic acid oxidation prepared in the current study are in the orders: Sb-Pt/GC2>Pb-Pt/GC2>Pb-Pt/GC1> Sb-Pt/GC1 >Pt/GC2>Pt/GC1>Pt.