Bimetallic Zeolitic Imidazolate Framework Derived Co₃O₄/CoFe₂O₄ Catalyst Loaded In₂O₃ Nanofibers for Highly Sensitive and Selective Ethanol Sensing

In this study, pure and Co₃O₄/CoFe₂O₄-loaded Indium oxide (In₂O₃) nanofibers were synthesized by the electrospinning of an Indium/ Polyvinylpyrrolidone precursor solution containing cobalt and iron bimetallic zeolitic imidazolate frameworks and subsequent heat treatment. The ethanol, toluene, p-xylene, benzene, carbon monodxide, and hydrogen gas sensing characteristics of the solution were measured at 250-400 oC. 0.5 at%-Co₃O₄/CoFe₂O₄-loaded In₂O₃ nanofibers exhibited extreme response (resistance ratio - 1) to 5 ppm of ethanol (210.5) at 250 oC and excellent selectivity over the interfering gases. In contrast, pure In2O3 nanofibers exhibited relatively low responses to all the analyte gases and low selectivity above 250-400 oC. The superior response and selectivity toward ethanol is explained by the catalytic roles of Co3O4 and CoFe₂O₄ in gas sensing reaction and the electronic sensitization induced by the formation of p (Co₃O₄/CoFe₂O₄)-n (In₂O₃) junctions.