Hydrothermally grown porous FeVO4 nanorods and their integration as active material in gas-sensing devices

Abstract

Controllable fabrication of highly porous iron vanadate (FeVO₄) thick film consisting of disordered nanorods suitable for gas penetration and permeation was achieved by hydrothermal synthesis of fervanite-like FeVO₄·1.1H₂O. The subsequent dehydration to FeVO₄ was investigated by ⁵⁷Fe Mössbauer spectroscopy (Δ_QS), DTA, magnetic susceptibility (χ) and electron microscopy (REM/TEM). Their integration in gas sensing devices as porous layer via polymer-blended (PVDF) doctor-blading approach was successfully demonstrated followed by investigations of their electric properties and oxygen sensing capability. The probed I–U behaviour and UV-Vis measurements confirmed the semiconducting nature of triclinic FeVO₄ (E_g = 2.72 eV) and exhibited an activation energy for electric conduction of 0.46 eV. The best sensitivity of 0.29 ± 0.01 (m = −3.4 ± 0.1) could be obtained at an optimal working temperature of 250 °C.