Design of highly sensitive and selective ethanol sensor based on α-Fe₂O₃/Nb₂O₅ heterostructure

Abstract

The introduction of heterostructures is a new approach in gas sensing due to their easy and quick transport of charges. Herein, facile hydrothermal and solid-state techniques are employed to synthesize an α-Fe2O3/Nb2O5 heterostructure. The morphology, microstructure, crystallinity and surface composition of the synthesized heterostructures are investigated by scanning electron microscope, transmission electron microscope, x-ray diffraction, x-ray photoelectron spectroscopy and Brunauer–Emmett–Teller analyses. The successful fabrication of the heterostructures was achieved via the mutual incorporation of α-Fe2O3 nanorods with Nb2O5 interconnected nanoparticles (INPs). A sensor based on the α-Fe2O3(0.09)/Nb2O5 heterostructure with a high surface area exhibited enhanced gas-sensing features, maintaining high selectivity and sensitivity, and a considerable recovery percentage towards ethanol gas. The sensing response of the α-Fe2O3(0.09)/Nb2O5 heterostructure at lower operating temperature (160 °C) is around nine times higher than a pure Nb2O5 (INP) sensor at 180 °C with the flow of 100 ppm ethanol gas. The sensors also show excellent selectivity, good long-term stability and a rapid response/recovery time (8s/2s, respectively) to ethanol. The superior electronic conductivity and upgraded sensitivity performance of gas sensors based on the α-Fe2O3(0.09)/Nb2O5 heterostructure are attributed due to its unique structural features, high specific surface area and the synergic effect of the n–n heterojunction. The promising results demonstrate the potential application of the α-Fe2O3(0.09)/Nb2O5 heterostructure as a good sensing material for the fabrication of ethanol sensors.

Tuning the π-Conjugation of 2-Thiohydantoins toward a Rigorously Defined Detection of Volatile Organic Compounds by Surface Photovoltage

“…The released electron occupies the vacancies produced, thus resulting in elevated sensing response. 26 The BFDH morphologies show that active sites on the surface of 2TH conjugate further support their interaction with VOCs. The crystal morphologies of Ph-2TH (Figure 11a) and Naptha-2TH (Figure 11b) reveal that C−H (aromatic) and CS functional groups were exposed as open sites for effective interaction with VOCs.…”

“…However, upon exposure to nonanal under dark and UV light illumination, the molecules of nonanal react with adsorbed oxygen with the release of electrons, thus reducing the height of depletion layer. The released electron occupies the vacancies produced, thus resulting in elevated sensing response …”

Heterojunctions on Ta2O5@MWCNT for Ultrasensitive Ethanol Sensing at Room Temperature

“…10 It is also worth mentioning that MOSs can adjust anion deficiencies and mix positive ion valences, which can prove the performance dramatically. A wide variety of MOC materials have been explored in gas sensing such as SnO 2 , 25 ZnO, 26 Fe 2 O 3 , 27 Co 3 O 4 , 28 and so on. To some extent, both n-type and p-type MOCs show gas sensing performance.…”

α-Fe2O3 thin films deposited by a facile spray pyrolysis technique for enhanced ethanol sensing

“…Due to their morphology, structure, chemical properties, and cost-effectiveness, gas sensor devices fabricated using metal-oxide semiconductors (MOSs) such as ZnO, SnO 2 , In 2 O 3 , TiO 2 , WO 3 , MoO 3 , and Fe 2 O 3 , and their composites have received widespread interest in recent decades [1][2][3][4][5]. Among MOS materials, iron oxide has been investigated extensively because of its unique chemical and physical properties [6][7][8][9][10][11][12]. Fe 3 O 4 (magnetite), FeO (wurtzite), α-Fe 2 O 3 (hematite), and γ-Fe 2 O 3 (maghemite) are the four distinct crystalline phases of iron oxide [13].…”