Novel preparation of functional β-SiC fiber based In2O3 nanocomposite and controlling of influence factors for the chemical gas sensing

The gas sensing ability of a pure β-SiC fiber is limited due to its low-sensitivity and selectivity with poor recovery time during a gas sensing test. The combination of functional β-SiC fibers with metal-oxide (MO) can lead to excellent electronic conductivity, boosted chemical activity, and high reaction activity with the target gas and β-SiC–In₂O₃ sensor material. Influence factors such as amounts of MO, current collectors, and gas species (CO₂, O₂ and without gas) for the gas sensing ability of β-SiC–In₂O₃ nanocomposite were determined at standard room temperature (25 °C) and high temperature (350 °C) conditions. The gas sensing ability of the functional β-SiC fiber was significantly enhanced by the loading of In₂O₃ metal-oxide. In addition, the MO junction on the β-SiC fiber was mainly subjected to the Si–C–O–In bond sensor layer with an effective electron-transfer ability. The gas sensing mechanism was based on the transfer of charges, in which the sensing material acted as an absorber or a donor of charges. The sensor material could use different current- collectors to support the electron transfer and gas sensing ability of the material. A 1:0.5M SiC–In₂O₃ coated Ni-foil current collector sensor showed better sensing ability for CO₂ and O₂ gases than other gas sensors at room temperature and high temperature conditions. The sensing result of the electrode was obtained with different current density values without or with gas purging conditions because CO₂ and O₂ gases had electron acceptor properties. During the gas sensing test, the sensor material donated electrons to target gases. The current value on the CV graph then significantly changed. Our obtained sample analysis data and the gas sensing test adequately demonstrated that MO junctions on functional β-SiC fibers could improve the sensitivity of a sensor material and particularly upgrade the sensor material for gas sensing.

Facile metal-organic frameworks-templated fabrication of hollow indium oxide microstructures for chlorine detection at low temperature

Metal oxides with the hollow microstructure by the facile synthetic strategy are hopeful in applications for photocatalysis, supercapacitor, and gas sensor owing to their large surface areas, porosity ratio and rich active sites. In this work, indium oxide porous hollow rods (In₂O₃ PHRs) are successfully prepared using metal-organic frameworks (MOFs) as the template. The morphology of In₂O₃ PHRs is hexagonal hollow micro-rods with a porous structure. The investigation on the gas-sensing performance reveals that the In₂O₃ PHRs sensor displays outstanding sensitivity and selectivity toward 10 ppm chlorine gas (Cl₂) at low operational temperature (160 °C). Furthermore, the In₂O₃ PHRs sensor displays a low detection limit (3.2 ppb) and short response and recovery time (38/13 s). The unique morphology and abundant oxygen vacancies are conduced to the excellent gas-sensing activities, which is benefited from the utilization and decomposition of In-MOFs precursor. In addition, the gas sensing mechanism of reducing gases and oxidizing gases is deduced in detail for the In₂O₃ PHRs sensor.

Flexible ultra-sensitive and resistive NO2 gas sensor based on nanostructured Zn(x)Fe(1−x)2O4

Low concentration gas detection, rapid response time and low working temperature are anticipated for a varied range of toxic gas detection applications. Conversely, the existing gas sensors suffer mostly from a high working temperature along with a slow response at low concentrations of analytes. Here, we report an ultrasensitive flexible nanostructured Zn_(x)Fe_(1−x)2O₄ (x = 0.1, 0.5 and 0.9) based chemiresistive sensor for nitrogen dioxide (NO₂) detection. We evince that the prepared flexible sensor Zn_(0.5)Fe_(0.5)2O₄ has detection potential as low as 5 ppm at a working temperature of 90 °C in a short phase. Further, the Zn_(0.5)Fe_(0.5)2O₄ sensor exhibits excellent selectivity, stability and repeatability. The optimized sensor sensing characteristics can be helpful in tremendous development of foldable mobile devices for environmental monitoring, protection and control.

Low concentration gas detection, rapid response time and low working temperature are anticipated for a varied range of toxic gas detection applications.

Hydrothermal synthesis and Cl2 sensing performance of porous-sheets-like In2O3 structures with phase transformation

Phase transformation (bcc-In₂O₃ to rh-In₂O₃) and high Cl₂ sensing performance of Fe doped porous-sheets-like In₂O₃.

Zn-doped In2O3 hollow spheres: mild solution reaction synthesis and enhanced Cl2 sensing performance

Microstructures and Cl₂-sensing performances of Zn-doped In₂O₃ hollow spheres.