The distinctive sensing performance of cobalt ion in LaBO3 perovskite (B = Fe, Mn, Ni, or Cr) for hydrazine electrooxidation

Abstract

A single phase rhombohedral LaCoO3 perovskite is prepared by the microwave-assistant citrate method. The as-synthesized perovskite is applied as a facile sensor for hydrazine determination in aqueous 1 M KOH by using electrochemical techniques such as cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). The cyclic volyammogram of LaCoO3 modified glassy carbon electrode (GC/LaCoO3) show a well-defined hydrazine oxidation peak of a current, Ip, equals 1.71 mA·cm−2 at an oxidation peak potential, Ep, of +518.8 mV vs. Ag/AgCl. On the other hand, no hydrazine oxidation is observed at modified GC electrodes with other lanthanum-transition metals perovskites, LaBO3 (B is Ni, Mn, Cr, or Fe). EIS data showed a reduction of the charge-transfer resistance value from 220.9 to 3.8 Ω·cm2 by casting LaCoO3 on GC electrode surface, reflecting the powerful electrocatlaytic activity of LaCoO3 towards the hydrazine oxidation. The presented sensor has two linear responses over hydrazine concentration ranges 0.1–15 and 20–60 mM, with sensitivity values of 5.61 mA·cm−2. M−1 and limit of detection (LOD) value of 0.15 nM, respectively. The sensor exhibits a high stability, excellent reproducibility and accepted anti-interferences ability for various inorganic ions and organic compounds.