Effect of synthesis method and morphology on the enhanced CO2 sensing properties of magnesium ferrite MgFe2O4

The synthesis and characterization of magnesium ferrite MgFe2O4 prepared by co-precipitation and sol gel combustion is reported. Structural characterization showed that all the samples have single spinel phase. The co-precipitated sample exhibits smaller grains and twice higher BET surface than the sol gel combustion samples. The powder was shaped to dedicated chemo-resistive home-made sensors devices. The electrical properties and sensing properties towards carbon dioxide of both MgFe2O4 powders were studied. The type of charge carriers were analysed on the basis of the change in resistance in the presence of air and argon. The sensing response towards CO2 was found to be dependent on the morphology of the powder sample and the CO2 concentration. A high response of 36% towards 5000 ppm of CO2 was reached which is good for this gas. The key role of the Mg ions modulating the electrical properties is discussed. •Two synthesis methods (co-precipitation and solgel combustion) yielded same structure with different microstructure.•A response of up to 36% could be obtained for the first time for CO2 sensing with magnesium ferrite powders.•Mg-ferrite generates different reaction mechanisms with gas than other spinel ferrite.•Air/Ar measurements confirmed the charge carriers where n-type in both samples.