Synthesis of Vertically Aligned Manganese-Doped Fe₃O₄ Nanowire Arrays and Their Excellent Room-Temperature Gas Sensing Ability

Abstract

Vertically aligned Mn (10%)-doped Fe 3 O 4 (Fe 2.7 Mn 0.3 O 4 ) nanowire arrays were produced by the reduction/ substitution of pregrown Fe 2 O 3 nanowires. These nanowires were ferromagnetic with a Verwey temperature of 129 K. X-ray magnetic circular dichroism measurements revealed that the Mn 2+ ions preferentially occupy the tetrahedral sites, substituting for the Fe 3+ ions. We observed that the Mn substitution decreases the magnetization, but increases the electrical conductivity. We developed highly sensitive gas sensors using these nanowire arrays, operating at room temperature, whose sensitivity showed a correlation with their bond strength of diatomic/triatomic molecules.

Enhancement of ethanol gas sensing response based on ordered V2O5 nanowire microyarns

“…It can be seen that the yarn-based gas sensor presents response to these four types of testing gases, which would due to the oxidation and hydrogenbonding polarity of the gas molecules. The hydrogen-bonding polar gas molecules have the distinction of larger electron donating ability of the electron-rich N or O atoms [32]. During the measurements of response transient of the microyarn toward testing gases, the response time ascends in the order of CH 3 OH, C 2 H 5 OH, NH 3 , and C 6 H 5 CH 3 , but the response magnitude is different and ascends in the order of NH 3 , CH 3 OH, C 6 H 5 CH 3 , and C 2 H 5 OH.…”

“…If yarns are located between two electrodes orderly, the agglomeration of nanowires can be prevented effectively, which make more surfaces exposed to the testing gas than in the randomly oriented nanowires. What is more important, the orderly assembled yarns provide a direct path for electron transfer [19,32,43], the conductometric response is basically determined by changes of the conduction channel along the nanowire. On the contrary, contact effects are reduced resulting in an enhanced gas sensing properties of orderly assembled V 2 O 5 nanowire yarns.…”

Growth of textured iron oxyhydroxide nanorod arrays on glass substrate

“…In addition, these integrated nanostructures show interesting magnetic properties [5] or improved quantum efficiency [6,7]. Particularly, arrays of 1D iron (oxyhydr)oxide nanostructure have attracted much attention owing to their potential for serving as template [8][9][10] and wide applications in solar cells, gas sensors, catalysts, as well as cathodes for lithium-ion batteries [11][12][13][14].…”

Tailoring the Number of Junctions per Electrode Pair in Networked ZnO Nanowire Sensors

“…In recent years, a number of approaches to overcome the shortcomings of single nanowire gas sensors have been reported. One approach is the use of vertically aligned nanowire arrays, wherein metal electrodes are deposited either on the top or bottom of nanowire arrays, consequently leading to the participation of multiple nanowires in the sensing process. Another approach is to use randomly networked nanowires, in which multiple nanowires are also involved .…”