退火处理对碳载Pt-Ru-Ni催化剂稳定性的影响

Effect of annealing heat treatment on stability of Pt-Ru-Ni/C catalyst for direct methanol fuel cell

为了提高直接甲醇燃料电池的阳极催化剂稳定性,对浸渍还原法制备的Pt-Ru-Ni/C催化剂进行退火处理,研究了处理工艺参数对催化剂活性和稳定性的影响;利用玻碳电极测试了处理过的催化剂在0.5mol/L甲醇和0.5mol/L硫酸混合溶液中的循环伏安曲线和计时安培电流曲线,考核了催化剂对甲醇电催化氧化活性和稳定性;通过X射线衍射(XRD)技术对催化剂的晶体结构进行了分析。结果表明,随着处理温度升高,催化剂晶格参数减小,粒径显著增大;随着处理时间延长,催化剂晶格参数同样减小,粒径增大幅度不大。电化学测试表明,退火处理有利于提高Pt-Ru-Ni/C催化剂的稳定性;在退火工艺参数范围内,200℃退火处理2h为较好的工艺条件。

This research is aimed to increase the activity and stability of anodic catalysts and thus to lower noble metal and the catalyst loading in anodes for methanol electrooxidation. The direct methanol fuel cell （DMFC） Pt-Ru-Ni/C anodic catalysts prepared by chemical reduction were annealed heat treatment at different temperatures and for different times. Their performance were tested using a glassy carbon working electrode through cyclic voltammetric curves and chronoamperometric curves in a solution of 0.5 mol/L CH3OH and 0.5 mol/L H2SO4; The particle sizes and their structures of the catalysts were determined by means of X-ray diffraction （XRD）. XRD analysis shows that the lattice parameters decrease and particle sizes markedly increase with the increase of treatment temperatures; the lattice parameters also decreases and particle sizes slightly increases with treatment times. The electrochemical measurements show that the annealing heat treatment can improve the stability of Pt-Ru-Ni/C catalysts. It is a better condition that the annealing heat treatment is carried out at 200 ℃ for 2 h in present work.