High performance ethanol and acetone gas sensor based nanocrystalline MnCo2O4 using clad-modified fiber optic gas sensor

Development of ethanol and acetone gas sensing performance of MgCo2O4 nanosensors by clad modified fiber optical method

Development of highly effective and environmentally friendly battery technology is crucial to the energy storage system and electronic vehicle.[1,2] Recently, the aprotic lithium-oxygen (Li-O2) battery has attracted much attention due to its high specific energy density of 3500 Wh kg-1 (based on the mass of Li2O2) and a favorable potential of 3.0 V, which are defined by the chemistry of the reversible reaction Li + O2 ↔Li2O2.[3,4] The high specific energy density of Li-O2 battery renders it a promising candidate for the electrical vehicle with extended-range driving. One of the challenges in Li-O2battery is to find a catalyst that can improve the sluggish electrochemical kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) during the discharge and charge process, respectively.[5] Herein, we employ Magneli phase Ti4O7 as a support and construct a hybrid with MnCo2O4 (MCO) nanoparticles being anchored on the surface of Ti4O7 for the first time. This hybrid is employed as a non-carbon cathode material for Li-O2 batteries. The synergistic interaction between Ti4O7 support and MCO nanoparticles further promotes the catalytic activity and stability of the hybrid. Benefiting form these advantages, the as-synthesized Ti4O7-MCO hybrid exhibits excellent catalytic activity to decrease the voltage gap between discharge and charge. The Ti4O7-MCO presents excellent discharge performance when compared with other carbon-free cathode materials. Moreover, due to the excellent chemical durability of Ti4O7 in organic electrolyte and the interaction between Ti4O7and MCO, the hybird is very stable during the battery cycling without agglomeration and detachment. The Discharge/charge profile, rate capability and cycling performance of Ti4O7-MCO are shown in Figure 1. Figure 1. (a) Discharge/charge profile of Ti4O7-MCO cathode under different current densities; (b) First discharge/charge profile of Ti4O7-MCO, Ti4O7, C and C-MCO with a limited capacity of 500 mAh g-1; (c) Cycling performance of Ti4O7 cathode; (d) Cycling performance of Ti4O7-MCO cathode. Acknowledgements This work is supported by National Natural Science Foundation of China (51572181), the National Key Research and Development Program of China (2016YFB0100200)，Natural Science Foundation of Jiangsu Province, China (BK20151226).

Fiber optic room temperature ethanol sensor based on ZnSnO3/TiO2 with UV radiation sensitization

The design and fabrication of low-cost and fast-response α-Ag2WO4 nanoparticle sensors for the detection of gases like ethanol, ammonia and acetone are reported. Silver tungstate nanocrystals were prepared by a chemical precipitation method, and were characterized by x-ray diffraction, transmission electron microscopy and conductometric methods. The gas-sensing characteristics of α-Ag2WO4 nanoparticles fabricated in the form of thin wafers without any sensitizer coating are reported. The sensor responses of α-Ag2WO4 nanoparticles for ethanol, ammonia and acetone gases were measured as a function of temperature. All the gases showed excellent and fast sensor responses, good repeatability and short recovery times for α-Ag2WO4 nanoparticles.

Ultra-sensitive determination of epinephrine based on TiO2-Au nanoclusters supported on reduced graphene oxide and carbon nanotube hybrid nanocomposites

Protocols for sputtering stoichiometric aluminum antimonide thin films were developed by calculating aluminum and antimony vapor condensation flux densities. Aluminum and antimony were sputtered separately. The high chemical reactivity of nanosized aluminum and antimony films made it possible to reduce the synthesis temperature considerably (far below the melting point of the compound). The synthesis involved thermal annealing. The reaction between aluminum and antimony films started at 470°С. Optimal AlSb formation parameters comprise annealing at 540°С for at least 10 h. Film synthesis steps were studied by X-ray powder diffraction, optical, electron, and atomic force microscopy. The composition was monitored by energy dispersive X-ray spectra. The films were found to have hole conductivity; the 300-K charge density and charge mobility in the films are 1 × 1019 cm–3 and 1 × 102 cm2/(V s), respectively.

A menace of antimicrobial resistance with growing difficulties in eradicating clinical pathogens owing to the biofilm has prompted us to take up a facile aqueous-phase approach for the synthesis of silver nanowires (SNWs) by using ethylene glycol as a reducing agent and polyvinylpyrrolidone (PVP) as a capping agent. This synthesis is a reflux reaction seedless process. The obtained SNWs were about 200-250 nm in diameter and up to 3-4 μm in length. The SNWs were characterized by field emission scanning electron microscopy, transmission electron microscopy, UV-Vis spectroscopy, and X-Ray powder diffraction, and the chemical composition of the sample was examined by energy dispersive X-ray spectrum. The SNWs did not show an antibacterial activity against test organisms, Bacillus subtilis NCIM 2063 and Escherichia coli NCIM 2931; however, it showed a promising property of a quorum sensing-mediated inhibition of biofilm in Pseudomonas aeruginosa NCIM 2948 and violacein synthesis in Chromobacterium violaceum ATCC 12472, which is hitherto unattempted, by polyol approach.

A simple microwave-assisted combustion synthesis and structural, optical and magnetic characterization of ZnO nanoplatelets

Synthesis, spectral, crystal structures, Hirshfeld surface analysis and DFT studies on phenylmercury(II) dithiocarbamate complexes and their utility for the preparation of mercury sulfide nanoparticles

The Makoro kaolin deposit, southeastern Botswana: its genesis and possible industrial applications

Influence of Yttrium on optical, structural and photoluminescence properties of ZnO nanopowders by sol–gel method

Zn0.96−xFe0.04CuxO (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10) nanopowders have been synthesized by sol–gel method. The synthesized samples have been characterized by powder X-ray diffraction, energy dispersive X-ray spectra, X-ray photoelectron spectroscopy, UV–visible spectrophotometer and Fourier transform infrared spectroscopy. The XRD measurement reveals that the prepared nanopowders have different microstructure without changing a hexagonal wurtzite structure. The calculated average crystalline size increases from 20.9 to 22.1 nm for x = 0 to 0.02 then gradually decreases to 18.2 nm for x = 0.10 which were confirmed by SEM and TEM micrographs. The change in lattice parameters, micro-strain, and shift of X-ray diffraction peaks towards lower angles and increase of energy gap reveal the substitution of Cu2+ ions into Zn–Fe–O matrix. X-ray photoelectron spectroscopy study described the increase of oxygen vacancies with increase of Cu concentrations, which was found to enhance the green emission. The presence of functional groups and the chemical bonding is confirmed by FTIR spectra. Photoluminescence spectra of Zn0.96−xFe0.04CuxO system shows that the blue shift in NBE ultraviolet emission from 389 to 369 nm and the same blue shift in green band emission from 552 to 535 nm with enhancing intensity confirms the substitution of Cu into the Zn–Fe–O lattice. Cu-doped Zn0.96−xFe0.04CuxO system is appreciable for the fabrication of nano-optoelectronic devices like tunable light emitting diode in the near future.

Structural, optical, FTIR and photoluminescence properties of Zn0.96−xCo0.04CuxO (x=0.03, 0.04 and 0.05) nanopowders

High-performance ethanol gas sensors are in high demand for various clinical and environmental monitoring applications. In this study, we developed a high-performance ethanol gas sensor using pure SnO2 nanoflakes. These nanoflakes were synthesized through a hydrothermal method and subsequently annealed at different temperatures to investigate the impact of annealing temperature on sensor performance. Among the samples tested, the ethanol gas sensor based on SnO2 annealed at 300 °C exhibited a higher response to ethanol than other samples toward 20 and 1000 ppm ethanol gas at 200 °C. The fast response and good selectivity confirm that the SnO2 nanoflakes annealed at 300 °C can be a promising sensing material for the fabrication of ethanol gas sensors.

Microporous dinuclear copper(II) trans-1,4-cyclohexanedicarboxylate: heterogeneous oxidation catalysis with hydrogen peroxide and X-ray powder structure of peroxo copper(II) intermediate