热处理对双核铁酞菁电催化氧还原反应的影响

Electrocatalytic effect of binuclear iron phthaiocyanine (bi-FePc) after heat treatment on oxygen reduction reaction in alkaline solutions

研究了Ar气氛中、不同热处理温度对双核单金属铁酞菁(bi-FePc)催化气体扩散电极上氧还原反应(ORR)的影响。采用紫外-可见光谱和热重-差热(TG-DTG)对bi-FePc的热稳定性进行分析;采用极化曲线法和交流阻抗法对电极性能进行了测试,并与没有催化剂的C电极进行了比较。研究发现热处理的bi-FePc对于氧的还原反应有着显著的影响,经过600℃处理后bi-FePc的催化效果最为明显,交流阻抗Nyquist图谱均显示了两个半圆的特征,采用Zview2.0阻抗谱分析软件对-0.2V(vs.Hg/HgO)电位下的各交流阻抗图谱进行等效电路拟合,提出空气电极ORR反应的等效电路,说明氧在空气扩散电极上的还原反应由一电子转移步骤和随后的化学反应组成,并对等效电路中各动力学参数进行了解释。

The electrocatalytic effect of different temperatures at flowing argon atmosphere on the oxygen reduction reaction （ORR） of gas diffusion electrode in alkaline medium for binuclear iron phthaiocyanine （bi-FePc） was studied. The heat stability of bi-FePc was analyzed by UV-vis spectrum and TG/DTG plot. The electrochemical measurements such as cathode polarization curves and electrochemical impedance spectroscopy （EIS） were used to analyze this kind of effects of those electrocatalysts. Compared with the carbon electrode, the electrocatalytic activity for ORR of bi-FePc with the heat treatment was improved obviously, especially, after the heat treatment at 600 ℃. The characteristic of two semi-circles on the gas diffusion electrode was presented on the EIS Nyquist plot. The equivalent circuit for ORR on the gas diffusion electrode shows that ORR obeys the single charge transfer followed by the chemical reaction, is proposed based on the results of EIS at the potential -0.2 V vs.Hg/HgO with the analytical software Zview2.0. The simulated kinetics data of the equivalent circuit was also analyzed.