载体表面化学状态对Pt/C催化剂结构及电催化活性的影响

The effect of surface chemical state of supports on structure and electrocatalytic activity of Pt/C electrocatalysts

对碳黑进行不同条件的氧化处理得到不同表面化学状态的载体,以甲醛为还原剂,氯铂酸为前驱体,制备Pt/C电催化剂。运用X射线光电子能谱(XPS)、X射线衍射(XRD)、透射电镜(TEM)等分析手段研究碳黑及Pt/C催化剂的化学组成、化学状态、晶体结构及表面形貌,并用循环伏安法(CV)测试Pt/C催化剂对甲醇的电催化氧化。结果表明,碳黑经氧化处理,表面的化学组成和化学状态均发生了变化,表面的含氧官能团浓度显著增加,增加的含氧官能团为碳黑表面沉积Pt提供了更多锚位,改善了碳黑表面Pt纳米粒子的分散性,降低了Pt纳米粒子的尺寸,使Pt/C催化剂中PtO的含量减少,Pt0含量明显增加,从而提高了Pt/C催化剂对CH3OH氧化的电催化活性。

A series of carbon black supports with different surface chemical state were prepared with the oxidation treatment of Vulcan XC-72 carbon black.Pt/C catalysts were fabricated with formaldehyde as the reducing agent and hydrochloroplatinic acid as the precursor.The chemical composition,chemical state,crystal structure and surface morphology of carbon black supports and Pt/C catalysts were respectively studied by X-ray photoelectron spectroscopy（XPS）,X-ray diffraction（XRD）and transmission electron microscope（TEM）,and electrocatalytic activity of Pt/C catalysts toward methanol oxidation were measured by cyclic voltammetry（CV）.The results indicate that,through the oxidation treatment,the chemical composition and chemical state of carbon black are both changed,the concentration of surface oxygen-containing function group increases,the increased oxygen-containing function groups offer more anchor sites for Pt deposition,improve the dispersity of Pt nanoparticles on the surface of carbon black supports,decrease the size of Pt nanoparticles,and cause the reduction of the PtO content in Pt/C electrocatalysts,thus enhance the electrocatalytic activity of Pt/C electrocatalysts toward methanol oxidation.