Nanocasting synthesis, magnetic interaction and gas-sensing properties of dispersed, bundled and assembled α-Fe2O3 nanowires
Nanocasting synthesis, magnetic interaction and gas-sensing properties of dispersed, bundled and assembled α-Fe2O3 nanowires
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DOI：
10.1016/j.jallcom.2017.01.118
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发表时间：
2017-05
影响因子：
6.2
通讯作者：
Xiaojiong Chen;Junqi Wei;Xinyou Wang;Panfeng Wang
中科院分区：
文献类型：
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作者：
Xiaojiong Chen;Junqi Wei;Xinyou Wang;Panfeng Wang
以SBA-15为硬模板，采用纳米铸造的方法合成α-Fe2O3（赤铁矿）纳米线，并通过离心技术将其分为分散型α-Fe2O3纳米线（DNWs）、捆绑型α-Fe2O3纳米线（BNWs）和组装型α-Fe2O3纳米线（ANWs）。采用x射线衍射（XRD）、透射电子显微镜（TEM）、氮气吸附/解吸等温线、紫外可见光谱和超导量子干涉仪（SQUID）对样品进行了表征。结果表明，在纳米线直径相同的情况下，合成样品的纳米线间距存在较大差异。磁测结果表明，α-Fe2O3ANWs和BNWs的Ms小于α-Fe2O3DNWs， Hc和TC大于α-Fe2O3DNWs。这可能是由于α-Fe2O3ANWs和BNWs相邻纳米线之间的间距较小，产生了表面自旋耦合的磁相互作用。气敏行为表明，α-Fe2O3ANWs、BNWs和DNWs对乙醇具有优异的气敏性能，这是由于α- fe2o3纳米线具有较宽的禁带。灵敏度随比表面积的增加而增加，α-Fe2O3DNWs传感器的灵敏度高于α-Fe2O3BNWs和ANWs传感器。基于α-Fe2O3ANWs、BNWs和DNWs的传感器在低浓度下具有快速的响应和恢复时间（仅为7 s和1 s）以及优异的气敏性。
The α-Fe2O3(hematite) nanowires were synthesized with the nanocasting route using the hard template of SBA-15, and then were divided into the dispersed α-Fe2O3nanowires (DNWs), bundled α-Fe2O3nanowires (BNWs) and assembled α-Fe2O3nanowires (ANWs) by the centrifugation technique. All samples were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherm, UV–vis spectrum and superconducting quantum interference device (SQUID). All results indicated that all synthesized samples with the same nanowires diameter presented the much different interwires distance. Magnetic measurements showed that Ms of α-Fe2O3ANWs and BNWs was smaller than that of α-Fe2O3DNWs, while Hc and TC were larger than α-Fe2O3DNWs. These should be attributed to the magnetic interaction from the surface spin coupling for the smaller interwires distance between the neighboring nanowires of α-Fe2O3ANWs and BNWs. The gas-sensing behavior indicated that the as-obtained α-Fe2O3ANWs, BNWs and DNWs exhibited the excellent gas-sensing performance to ethanol, resulting from the wide bandgap of α-Fe2O3nanowires. Furthermore, it was proved that the sensitivity increased with the specific surface area, and the sensitivity of α-Fe2O3DNWs based sensors was higher than those of α-Fe2O3BNWs and ANWs. The α-Fe2O3ANWs, BNWs and DNWs based sensors presented the rapid response and recovery times (only 7 s and 1 s) and the excellent gas sensitivity at low concentration.