氧还原电催化剂Pt/WO3-C的制备及稳定性研究

采用化学沉淀法由HCl-Na₂WO₄制备WO₃-C复合载体, 通过微波辅助乙二醇还原法制备Pt/WO₃-C复合载体催化剂。研究了WO₃含量以及热处理温度对Pt/WO₃-C催化剂性能的影响, 采用X射线衍射、透射电子显微镜和能量散射光谱对Pt/WO₃-C的物化结构和组成进行了表征。结果表明, WO₃的最佳含量为10wt%, N₂气氛中热处理适宜温度为250℃。所制备的Pt/WO₃-C催化剂中WO₃以单斜晶型存在, Pt颗粒的平均粒径为2.77 nm。通过循环伏安法和单体质子交换膜燃料电池极化曲线测试了Pt/WO₃-C催化剂的电化学性能, 证实了Pt与WO₃之间存在协同催化作用, 与Pt/C催化剂相比, Pt/WO₃-C的催化活性和稳定性都有明显改善。

Synthesis of Pt/WO3-C as Catalyst for Oxygen Reduction Reaction and Its Evaluation of Stability

The WO₃-C hybrid materials were prepared by chemical precipitation reaction of hydrochloric and sodium tungstate in carbon suspension. Pt nanoparticles were deposited by microwave-assisted polyol process on WO₃-C. Influences of WO₃ contents and heat-treatment temperature on the catalytic activity for oxygen reduction and the single proton exchange membrane fuel cell performance were analyzed systematically. X-ray diffraction(XRD), transmission electron microscope (TEM) and energy dispersion spectrometry (EDS) were used to characterize the Pt/WO₃-C catalysts. The results show that the optimum content of WO₃ is 10wt%, and heat-treatment temperature in N₂ flow is 250℃. WO₃ presents as monoclinic phase and about 2.77 nm Pt metal crystallites disperse on WO₃-C. Cyclic voltammetry and polarization curves of single cells are investigated to measure the electrocatalytic activity. The synergistic catalytic effect is found between Pt and WO₃. The Pt/WO₃-C catalysts are more active for oxygen reduction than traditional Pt/C. The accelerated potential cycling test and single cell life test indicate that the Pt/WO₃-C catalysts possess substantially enhanced stability in comparison with Pt/C catalysts.