采用脉冲电沉积法制备了碳载的Pt-Ru-Ho电催化剂,循环伏安法(CV)和交流阻抗法(EIS)测定催化剂的甲醇电氧化活性,用XRD、EDS和XPS表征电催化剂的物性结构、表面元素组成和价态形式.结果表明,电催化剂中Pt,Ru,H0 3种元素以合金的形式存在,在合金表面有HoO存在,合金微粒粒径为3.5 nm,比表面积为73.3 m2.g-1;掺杂适量稀土金属Ho对Pt-Ru合金的活性有明显影响,其中原子比为npt:nRu:nHo=1:1:0.2时,Pt-Ru-Ho/C中Ho的含量较为适宜,电催剂的Tafel常数α减小,反应活化能低于Pt-Ru/C,为28.4 kJ·mol-1,催化活性明显高于Pt-Ru/C,但Ho含量过高Pt-Ru-Ho/C的活性低于Pt-Ru/C:Pt-Ru-Ho0 .2/C甲醇的反应级数为0.17级.
The Pt-Ru-Ho/C catalysts for methanol electro-oxidation have been prepared by pulse electro-deposition method. The activities of catalysts were characterized by cyclic voltammetry (CV) and electrochemical impedance spectrum (EIS). The micro-structure and composition of the catalysts were characterized by XRD, EDS and XPS. The results show that Pt-based alloy nano-particles supported on carbon black consist of Pt, Ru, Ho elements, and the particle size and the specific surface of catalysts are about 3.5 nm and 73.3 m2.g-1, respectively. The electro-catalytic activity of Pt-Ru/C can markedly be improved by doping with Ho. The optimum mole fraction in Pt-Ru-Ho alloy nano-particle is npt:nRu:nRu=1:1:0.2. Tafel constant a for Pt-Ru-Ho0.2/C is lower than that of Pt-Ru/C. The reaction order and the active energy of the methanol electro-oxidation are 0.17 and 28.4 KJ·mol-1. respectively.
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