Highly sensitive amperometric hydrazine sensor based on novel α-Fe2O3/crosslinked polyaniline nanocomposite modified glassy carbon electrode

Abstract

Fabrication of efficient chemical sensors is a prime strategy for detecting trace levels of environmental species, but predominantly limited by slow response time, relatively low sensitivity and poor selectivity. Here, we demonstrate, for the first time, the synthesis of a novel nanocomposite of α-Fe2O3/crosslinked polyaniline (α-Fe2O3/CPANI) via a simultaneous gelation and polymerization process. The newly prepared α-Fe2O3/CPANI nanocomposite was employed as an efficient hydrazine chemical sensor with high sensitivity and selectivity. The XRD, XPS and HR-TEM results confirmed the presence of PANI and revealed a well-crystalline, structurally uniform crystals of rhombohedral α-Fe2O3 phase with particle sizes <50 nm and distinctly lattice fringes of 3.7 Å. The electrochemical detection of hydrazine was conducted at α-Fe2O3/CPANI modified glassy carbon electrode (GCE) by the cyclic voltammetry and amperometry techniques and compared with bare GCE or pure α-Fe2O3. Comparing to bare GCE or pure α-Fe2O3, the α-Fe2O3/CPANI nanocomposite modified GCE shows a superior sensing performance, leading to a remarkable sensitivity of 1.93 μA μM-1 cm-2, a very low limit of detection (LOD) of 0.153 μM at (S/N = 3), a wide linear range of hydrazine concentrations from 0.2 μM to 40 μM, with a correlation coefficient (R2) = 0.9983 and a response time <12 s. Additionally, the present α-Fe2O3/CPANI modified electrode exhibits electrochemical stability and high selectivity as a negligible cross-sensitivity to common bio-active interfering species and several metal ions was observed. Furthermore, the electrocatalytic reaction obeys the first order kinetics with respect to hydrazine concentration with a diffusion dominated process. Such a novel nanocomposite of α-Fe2O3/CPANI represents a proper electrode material for highly efficient detection of hydrazine by electrochemistry.