In/Fe Cospinning Nanowires for Triethylamine Gas Sensing

Abstract

Solid solution is a type of substance with rich physicochemical properties and significant internal adjustability. Thus, it has been widely used in various areas, including gas sensing. In this study, several In/Fe oxide solid solutions were successfully synthesized using the cospinning method and annealing process. Affirmatively, the solute In 3+ substituted the original host Fe 3+ in lattices of iron oxide, and vice versa. Thus, phases of α-(Fe 1−x In x ) 2 O 3 and C-(Fe 1−x In x ) 2 O 3 solid solutions appeared in sequence as the proportion of In 3+ increased. When In 3+ was introduced, composite nanowires (NWs) became porous, but when the amount of In 3+ was increased, the gas permeability worsened. When the amount of In 3+ became comparable to that of Fe 3+ in the precursor, abundant amorphous regions emerged in the product due to the mutual interference between the respective crystallization courses of In 3+ and Fe 3+ . Satisfactorily, the gassensing properties of as-synthesized samples maintained a close relationship with the composition and structure. For example, the product with the highest response and fastest response time toward the triethylamine detection had a 20.0 mol % ratio of In 3+ in the precursor. However, despite having a higher initial resistance, the sensor response was reduced by overproportioned amorphous phases caused by excessive In 3+ addition. Importantly, the response time of the optimal Fe 1.6 In 0.4 O 3 NWs was only 4 s, and recovery speeds of Fe 3+ -containing samples maintained a positive correlation with the gas permeability of products. Band stuctures of samples were obtained to give a reasonable explanation on the gas-sensitivity improvement. This study will promote the application of solid solutions to a gas-sensing area.