Pt/C和Pt/CNTs电极的电化学稳定性研究

采用恒电位氧化法研究了Pt/C和Pt/CNTs电极的电化学稳定性. 相同条件下, Pt/C电极的氧化电流大约为Pt/CNTs电极的2倍; 120 h氧化后, Pt/C电极Pt的电化学表面积下降了21.3%, 而Pt/CNTs电极仅下降了7.6%, 表明Pt/CNTs电极性能衰减较慢. X射线光电子能谱(XPS)分析表明, Pt/C的载体碳黑表面氧增加量大于Pt/CNTs中碳纳米管(CNTs)表面氧的增加量, 说明碳黑的被氧化程度较高, 电化学稳定性差; Pt的表面化学状态没有发生变化; 碳纳米管本身的抗电化学氧化性也大于碳黑. 所以, 载体的被氧化程度不同是两种电极性能衰减不同的主要原因之一, 并且排除了Pt表面状态的影响.

Study of the Electrochemical Stability of Pt/C and Pt/CNTs Electrodes

The electrochemical stability of carbon black supported and carbon nanotubes supported Pt (Pt/C and Pt/CNTs) electrodes was investigated using potentiostatic oxidation. The oxidation current of Pt/C is about twice of Pt/CNTs. During the 120 h holding at 1.2 V, the electrochemical surface area of Pt decreases 21.3% for Pt/C, but only 7.6% for Pt/CNTs, which implies that degradation rate is more slowly for Pt/CNTs. X-ray photoelectron spectroscopy (XPS) analysis shows that the oxidation degree of carbon black is higher than that of carbon nanotubes, and that the surface chemistry of Pt returns to the initial state after the ex- periment. It can be concluded that carbon nanotubes are more resistant to electrochemical oxidation than carbon black. Pt/CNTs is more stable than Pt/C. The higher electrochemical stability of Pt/CNTs is attributed to the higher resistance of carbon nanotubes to electrochemical oxidation, but not the change of Pt surface chemistry.