Size-tunable ferromagnetic ZnFe2O4 nanoparticles and their ethanol detection capabilities

Development of spinel-type zinc ferrite (ZnFe2O4) nanostructures that are able to efficiently detect Ethanol (C2H6O) gas at low working temperatures are currently hindered by their inadequate sensing performance. Herein, we report on ferromagnetic ZnFe2O4 nanoparticles (NPs) as a volatile organic compound sensing platform derived from a microwave-assisted hydrothermal method using KOH, NH4OH, and LiOH as base precursors in a controlled manner. Detailed structural findings revealed that the synthesized ZnFe2O4 NPs were of the face-centred cubic spinel structure with precisely tunable particle size of 23 nm, 22.5 nm, and 16 nm for the NPs derived from NH4OH, LiOH, and KOH base precursors, respectively. Based on the magnetic analysis results, all the ZnFe2O4 NPs displayed a ferromagnetic behaviour with NPs based on the NH4OH base precursor showing the smallest hysteresis loop among all the samples. To explore the effects of the base precursor variation, which correlated with a change in particle size of the ZnFe2O4 NPs, their sensing capabilities were evaluated. Findings pointed out that the ZnFe2O4 NPs sensor based on the NH4OH base precursor with the largest particle size demonstrated the highest gas sensing capabilities as well as improved selectivity to 40 ppm ethanol at 220 degrees C and good reproducibility owing to its magnetic behaviour, improved crystallinity and gas diffusion.