Localized Synthesis of Iron Oxide Nanowires and Fabrication of High Performance Nanosensors Based on a Single Fe₂O₃ Nanowire

Abstract

A composed morphology of iron oxide microstructures covered with very thin nanowires (NWs) with diameter of 15-50 nm has been presented. By oxidizing metallic Fe microparticles at 255 °C for 12 and 24 h, dense iron oxide NW networks bridging prepatterned Au/Cr pads are obtained. X-ray photoelectron spectroscopy studies reveal formation of α-Fe O and Fe O on the surface and it is confirmed by detailed high-resolution transmission electron microscopy and selected area electron diffraction (SAED) investigations that NWs are single phase α-Fe O and some domains of single phase Fe O . Localized synthesis of such nano- and microparticles directly on sensor platform/structure at 255 °C for 24 h and reoxidation at 650 °C for 0.2-2 h, yield in highly performance and reliable detection of acetone vapor with fast response and recovery times. First nanosensors on a single α-Fe O nanowire are fabricated and studied showing excellent performances and an increase in acetone response by decrease of their diameter was developed. The facile technological approach enables this nanomaterial as candidate for a range of applications in the field of nanoelectronics such as nanosensors and biomedicine devices, especially for breath analysis in the treatment of diabetes patients.

ZnAl2O4‐Functionalized Zinc Oxide Microstructures for Highly Selective Hydrogen Gas Sensing Applications

“…In the case of the ZnAl 2 O 4 /ZnO MW, the well distributed ZnAl 2 O 4 nanocrystals along the MW can be spotted easily, while the diameter of nanocrystals varies from 10 to 50 nm (see Figure a). Because the diameter is the main parameter which determines the performances of individual devices, these two devices with practically the same diameter will be used in order to compare the reported two methods.…”

“…Thus, the main gas sensing mechanism in the case of individual structures is the modulation of the electron depletion region, respective of the conduction channel under exposure to reducing or oxidizing gases . Therefore, the structure diameter plays a major role for the gas sensing performances . It was experimentally demonstrated that the lower the diameter, the higher the gas response which can be obtained based on individual metal oxide nanostructures .…”

“…Therefore, the structure diameter plays a major role for the gas sensing performances . It was experimentally demonstrated that the lower the diameter, the higher the gas response which can be obtained based on individual metal oxide nanostructures . This can be explained based on the higher modulation of the conduction channel width in the case of a lower nanostructure diameter, especially when the radius is comparable to the Debye length .…”

“…Therefore, the formation of Schottky contacts based on Pd or Pt due to the high catalytic effect of such noble metals can induce the H 2 sensing properties, too, for such materials as carbon nanotubes (CNTs) and Si, which normally are not sensible to H 2 gas at room temperature . The detailed gas sensing mechanism with representation of the energy band diagram for individual structures with single and double Schottky contacts was presented in our previous works …”

Al‐Doped ZnO Nanowires by Electrochemical Deposition for Selective VOC Nanosensor and Nanophotodetector

“…For the device fabrication, the nanowires were detached from the glass/FTO substrate using an ultrasonic equipment and spread on a SiO 2 (300 nm in thickness) coated Si wafers pre‐patterned with Cr/Au contact pads. Individual NWs were contacted on their both ends by platinum contacts using a focused ion beam/scanning electron microscopy (FIB/SEM) equipment according to the procedure described by Lupan et al More details on chip design and configuration of Au/Cr electrodes are presented in previous work . The UV and gas sensing properties were performed in a test chamber as described in previous papers .…”