Effects of Fe2O3 on the magnetic and gas sensing properties of Co3O4 nanoparticles

Abstract

Co3O4 and Fe2O3 composite nanoparticles with different Fe2O3/Co3O4 molar ratios were synthesized using the sol-gel auto-combustion method. The morphology and microstructure of the composite samples were studied by field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD). FESEM images highlighted the nanocomposite particles' spherical shape and uniform distribution, having an average size of 31±3 nm. XRD analysis revealed the presence of face centered cubic Fe2O3 and rhombohedral Co3O4 crystalline nanoparticles. The room temperature antiferromagnetic (RT-AFM) behavior of the composites was assessed by vibrating-sample magnetometry (VSM). This behavior was related to the interaction of the localized spins of the Co ions with the oxygen vacancies. I-V measurements highlight the ohmic behavior of the prepared samples, showing that the composites with higher Fe2O3 loading were the most noticeably conductive. Tests carried out demonstrated that the Fe2O3/Co3O4 composites proved suitable ethanol gas sensor towards low concentration (between 0 and 150 ppm) at low temperatures (150 °C) with quick response (2–10 sec) /recovery (18–50 sec) time and a LOD is around 4 ppm.

Keywords

• Nanoparticles
• Nanocomposites
• Iron oxide
• Cobalt oxide
• Sol-gel
• Magnetic properties