Catalytic and electrocatalytic properties of intrazeolitically prepared iron phthalocyanine

Abstract

Iron-phthalocyanine (FePc) has been successfully synthesised inside the pores of the NaY zeolite as evidenced by various physicochemical characterisation methods such as scanning electron microscopy (SEM), X-ray diffraction (XRD), electron spin resonance spectroscopy (ESR), ultraviolet spectroscopy (UV), cyclic voltammetry (CV) and thermal methods of analysis. XRD analysis indicates the formation of FePc molecules inside the supercages. SEM pictures show that the original microporous nature of NaY is not affected by encapsulation of FePc. ESR spectrum shows two peaks with g values of 1.977 and 4.030 indicating the partial oxidation of FePc in the cavity, while IR spectra suggest that the molecule can undergo a saddle deformation inside the zeolite matrix. In UV-Vis spectrum, the Q band of the FePc molecule is shifted from 656 nm to 686 nm, although the soret band is less affected. Thermal analysis indicates that these molecules have enhanced thermal stability inside the zeolite cavities. Cyclic voltammetric studies show that the electrochemical behaviour of pure FePc is not much affected by the encapsulation. The encapsulated FePc molecules are found to catalyse the hydrocarbon oxidation reactions. In addition, modified electrodes prepared with this material indicate good electrocatalytic effects as demonstrated by a 260 mV shift in the peak potential for oxygen reduction in neutral medium. Considerable electrocatalytic behaviour is also observed for oxidation of hydrazine.