In/Fe Cospinning Nanowires for Triethylamine Gas Sensing
Bo Zhang, Jing Wang, Pingping Yu, Lanlan Guo, Yin Xu, Yue Dong, Yi Ni, Jinping Ao, Qufu Weı, Yi Xia
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 In3+ substituted the original host Fe3+ in lattices of iron oxide, and vice versa. Thus, phases of α-(Fe1–xInx)2O3 and C-(Fe1–xInx)2O3 solid solutions appeared in sequence as the proportion of In3+ increased. When In3+ was introduced, composite nanowires (NWs) became porous, but when the amount of In3+ was increased, the gas permeability worsened. When the amount of In3+ became comparable to that of Fe3+ in the precursor, abundant amorphous regions emerged in the product due to the mutual interference between the respective crystallization courses of In3+ and Fe3+. Satisfactorily, the gas-sensing 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 In3+ in the precursor. However, despite having a higher initial resistance, the sensor response was reduced by overproportioned amorphous phases caused by excessive In3+ addition. Importantly, the response time of the optimal Fe1.6In0.4O3 NWs was only 4 s, and recovery speeds of Fe3+-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.