用X射线光电子能谱对热处理的四苯基钴卟啉修饰电极的表面表征

本文用XPS、DTA和TG分析了四苯基钴卟啉化学修饰电极的热分解行为, 它不同于四苯基铁卟啉. 由XPS谱图揭示了四苯基钴卟啉与玻璃碳电极之间的相互作用, 进而阐述了经热处理的四苯基钴卟啉化学修饰电极的表面结构与电催化稳定性的关系. 从Co2p_3/2和2p_(1/2)能级的自旋分裂间距及其Shake-up伴峰, 了解经热处理后的四苯基钴卟啉修饰电极中钴自旋态变化, 并且从Co的L_3VV俄歇跃迁计算出Co的双电离能, 其双电离能与电催化活性有一定关系。

SURFACE CHARACTERIZATION OF COBALT TETRAPHENYLPORPHYRIN MODIFIED GLASSY CARBON ELECTRODE BY XPS

Surface structure of the glassy carbon surface modified with cobalt tetraphenyl-porphyrin (CoTPP) by thermal-treatment has been studied by XPS, DTA and TG. During the thermal treatment a bond can be formed between the glassy carbon sur-face and TPP. Therefore the stability of electrode for the catalysis of dioxygen redu-ction is improved. Upon thermal treatment at 600 ℃, FWHM of Co(2p_(3/2)) is broa-dened, the reason is due to overlapping of peaks of multiple states; the spin orbit separation between Co(2p_(1/2)) and Co(2p_(3/2)) increases to 15.5—16.3 eV, which indicates a change from low spin divalent to high spin divalent states; the kinetic energy of Co L_3VV Auger line and Auger parameter also increase. These changes of central cobalt ion provide a suitable redox potential for Co(III)/Co(II) which is related to the activity for catalysis of dioxygen reduction.