化学修饰电极的研究 ⅩⅤⅡ四苯基铁卟啉化学修饰玻碳电极的热处理及其对氧的催化还原

关于金属卟啉、酞菁等化学修饰电极的研究已有大量工作发表.这类电极很不稳定,例如著名的面-面双钴卟啉修饰电报,虽然能直接催化氧还原为水,但经受不住几次电位扫描就失去催化活性.因此,如何提高稳定性就成为研究这类电极的关键.近年来有人报道,吸附在活性碳上的金属卟啉、酞菁类化合物经热处理,可改善其稳定性。热处理后得到的粉状碳催化剂,由于完全不溶于水及有机溶剂,制备电极非常困难。曾有过用这种

RESEARCHES ON CHEMICALLY MODIFIED ELECTRODE ⅩⅤⅡ. Electrocatalytic Reduction of Dioxygen by Iron Tetraphenylporphyrins Modified Glassy Carbon Electrode with Heat Treatment

The heat treatment of iron tetraphenylporphyrin chemically modified glassy carbon electrode has been described. The modified electrode by heat treatment shows good catalytic activity and stability for dioxygen reduction. Its catalytic activity is still maintained through 1000 cireles of cyclic voltametrie scans (100 V s~(-1)) in air saturated 0.05 mol L~(-1) H_2SO_4 solution. The effects of heat treatment temperature from 300 to 800 ℃ on the praparation and catalytic activity of the modified electrode have been studied. Using X.P.S, UV-VIS spectroscopy and Mass-spectroscopy the possible microstructure on electrode surface has been analyzed. The electrocatalytic and dynamic behaviors for dioxygen reduction at the electrode have been studied by cyclic voltametry and rotating disk electrode respectively. The rate constants of dioxygen reduction at the electrode in a variety of pH solutions have been measured. The catalytic reduction of dioxygen at this modified electrode belongs to irreversible processes including 2-electron to H_2O_2 and 4-electron to water.