Sol–Gel Synthesis and Electrochemical Sensing Properties of Brownmillerite Calcium Ferrite–Ca2Fe2O5 Nanoparticles

Nanocrystalline brownmillerite Ca 2 Fe 2 O 5 (CFO) has been prepared by sol–gel technique and the samples are presented as CFO1 and CFO2, for the products obtained at calcination temperatures of 600, and 800 ℃ respectively. The particles were characterized using optical and structural techniques, and were further evaluated for possible application in electrocatalysis. The diffraction patterns of the nanoparticles revealed a monocrystalline phase, consistent with the orthorhombic structure of brownmillerite Ca 2 Fe 2 O 5 . Absorption spectra showed a sharp absorption edge around 330 nm for CFO1, and a broad absorption band in the visible region (400–800 nm) for the CFO2. The external morphology presented porous flake-like agglomerates, with the internal morphology revealing a pseudo-spherical shape in both samples. The electrochemical studies of the nanoparticles including cyclic voltammetry, square wave voltammetry, and electrochemical impedance spectroscopy were carried out. The modified electrodes showed enhanced electroactive properties relative to the bare.