浸渍溶液中有机组分对Pt-Ru/C催化剂性能的影响

采用浸渍还原法制备Pt-Ru/C催化剂,选用不同的有机组分（如乙醇、异丙醇、四氢呋喃和乙二醇）组成浸渍溶液.这些有机组分与前驱体（PtC l62-和Ru^3＋离子）形成的配合物空间位阻的不同,直接影响前驱体在载体表面的吸附状况和还原电位,进而影响粒子尺寸、晶体结构和Pt-Ru/C催化剂的性能.实验表明,采用等体积比的乙二醇和水混合溶剂制备的Pt-Ru/C催化剂,透射电镜测试Pt-Ru粒子的平均粒径为2.7 nm,且粒径分布均匀;X射线衍射分析表明,Pt-Ru粒子相对结晶度低（IPt/IC=1.67）,合金化程度较高（Pt-Ru合金中Ru原子分数为0.471）.在0.5 mol/L H2SO4和0.5 mol/L CH3OH混合溶液中的循环伏安测试表明,所制备的Pt-Ru/C具有良好的催化活性和抗CO中毒能力.

Effect of Organic Composites in Impregnating Solution on Performance of Pt-Ru/C Catalysts

Pt-Ru/C catalysts have been prepared by impregnation-reduction method with various organic solvents, such as ethanol, isopropanol, tetrahydrofuran(THF) and glycol, as the impregnating solution. The steric hindrance of complexes formed from precursors (PtCl_6~(2-) and Ru~(3+) ions) and the organic solvents had direct impact on the adsorption on carbon black supports and the reduction potential values of precursors, which affected the particle size, crystal structure and the performance of Pt-Ru/C electrocatalysts. Experiment results show that Pt-Ru/C catalyst prepared from mixed solvent of glycol and water with a ratio of 1∶1 by volume has an even distribution of particle size and the average size of Pt-Ru particles is 2.7 nm by transmission electron microscopy (TEM). X-ray diffraction (XRD) analysis indicates a low relative crystallinity (I_(Pt)/I_C=1.67) and a high alloying degree for the Pt-Ru/C catalyst (Ru atom fraction in Pt-Ru alloy is 0.471). Cyclic voltammetry measurement results of the prepared Pt-Ru/C catalyst in 0.5 mol/L H_2SO_4 and 0.5 mol/L CH_3OH show good electrocatalytic performance and tolerance to CO of the catalyst.