Facile synthesis of hollow MnFe₂O₄ nanoboxes based on galvanic replacement reaction for fast and sensitive VOCs sensor

Hollow MnFe₂O₄ nanoparticles were successfully synthesized based on simple galvanic replacement reaction with Mn₃O₄ as a precursor. The chemical composition and nanostructure of the as-prepared samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. MnFe₂O₄ was applied to decorate interdigital electrodes and the obtained sensors were used to detect fourteen kinds of volatile organic compounds at different operation temperature from 160 °C to 280 °C. Results show that the sensor has good sensitivity, repeatability and long-term stability for ethanol gas determination at 210 °C. The detection linear range for ethanol is 2 ∼ 400 ppm, and the response and the recovery time was 7.5 s and 8.0 s, respectively. Besides, the fabricated sensor also displayed decent performance in measuring n-decane in the concentration range of 2 ∼ 400 ppm at 260 °C. Finally, gas-sensing mechanism of the prepared sensor was clearly studied.