Search

Industrialization can be greatly appreciated only by limiting the downside of the proposed technology. In this aeon, the recurrent monitoring of industries is statutory in detecting harmful gases and explosions for the global environment safety. Hence, employing specific gas sensors for detecting malicious gases benefits the welfare of the society. Thus, in this present work, we developed an energy efficient toxic gas sensor using ZnO thin film by seed layer assisted hydrothermal technique. The sensing mechanism of ZnO with the CO analyte was explained and the sensing parameters such as sensitivity, selectivity, response and recovery time were studied. Further, the developed energy efficient sensor was embedded with wireless sensor assembly for online monitoring which may be functional in developing portable, compact and cost-effective system for various real time industrial control applications.

Methane (CH4) gas, the second most potent greenhouse gas share a substantial role in contributing to the global warming and it is a necessary pre-requisite to detect the release of CH4 into the environment at its early stage to combat climate change. In that front, this work is focussed to develop an effective CH4 gas sensor using vanadium pentoxide (V2O5) thin films that works at an operating temperature of ∼100 °C. To understand the effect of sputtering power towards the structural characteristics of V2O5 films, X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) analysis were performed from which the orthorhombic polycrystalline structure of V2O5 thin films was confirmed with varied texture co-efficient. Further, the surface elemental studies using X-ray photoelectron spectroscopy (XPS) confirmed the prominence of V+5 oxidation state from the binding energy of V2p3/2 and O1s peak. The effect of sputtering power on the growth of different nanostructures were observed using field-emission scanning electron microscopy (FE-SEM). The critical role of adsorption and desorption kinetics of the deposited nanostructures were explained through first order kinetics based on Elovich model and the phase stability of different nanostructures were evaluated using Raman spectral analysis. This work achieved the sensor response of about ∼8% towards CH4 at an operating temperature of 100 °C towards 50 ppm concentration.

Heatstroke is a serious illness that can potentially damage many victims every year. Many intelligent physical sensors have been developed to prevent heatstroke fatalities. However, it remains a challenge to fabricate skin-adhesive, small, and low-cost sensors for in situ heatstroke detection to overcome the weaknesses of the physical sensors. As far as we know, this is the first breakthrough for exploiting a PDMS based freestanding nanosheet skin patch consisting of pH sensing elements (antimony/antimony oxide and silver/silver iodate) to achieve high pH sensitivity and repeatability. The sensing elements were investigated for structural and morphological properties. The easy to use and easy to fabricate nanosheet sensor exhibited a linear pH response of -43 mV/pH. Overall, the developed sensor showed high sensitivity, repeatability, and stability. Our initial results indicate that the developed sensor adhered well to a skin surface. It is expected that this proof of concept approach gives reliable fabrication and measurement unlike other physical sensors.

Mixed transition metal oxides (MTMOs) have recently been explored as building blocks for gas sensing applications due to their enhanced sensing characteristics. Here, we demonstrate the application of a co-sputtered V2O5–CdO thin film as a novel chemiresistive sensor for the detection of methane (CH4) gas. From X-ray diffraction (XRD) studies, the mixed phase was identified as polycrystalline cadmium metavanadate (CdV2O6), and from X-ray photoelectron spectroscopy (XPS) studies, the clear existence of V5+ and Cd2+, corresponding to V2O5–CdO, was observed. The obtained mixed phase featured fused nanorod-like structure with ∼450 nm thickness. By monitoring the sequential sensing characteristics over various temperature (RT-150 °C) and concentration (25–500 ppm) range, the optimum operating temperature (100 °C) was identified. The polycrystalline V2O5–CdO sensor exhibited a response of ∼1.72% towards 25 ppm CH4 at 100 °C. The use of evenly co-sputtered semiconductive (Cd2+ and V5+) nanorods will provide advanced routes towards the development of various devices based on MTMOs.

Zeolites are commercially used crystalline microporous materials. Understanding their crystallization mechanism and corresponding synthesis development is still of scientific and technological sign...

The present work deals in developing mixed compounds of vanadium sesquioxide (V2O3) and cuprous oxide (Cu2O) thin films using direct current (dc) magnetron co-sputtering technique for the detection of trimethylamine (TMA) vapour at ambient temperature (∼30 °C). The X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) characterizations confirmed the amorphous nature of V2O3-Cu2O thin film. The chemical stoichiometry of the mixed oxide film was determined as V+3 and Cu+1 oxidation states using X-ray photoelectron spectroscopy (XPS) analysis. The nanograin like morphology with an average particle size and thickness of about ∼15 and ∼85 nm was observed from field-emission scanning electron microscopy (FE-SEM). The TMA sensing studies proved that the sensor can detect a minimum of 3 ppm concentration with a sensor response (S = Ra/Rg) of ∼1.08. The developed sensor exhibited better sensitivity towards amine groups than alcohol, aldehyde, and ketone groups. Hence, it is believed that the developed Cu2O–V2O3 (VCO) mixed oxide can be a better amine sensor that can be utilized for the determination of fish quality.

Zeolites Y from organic-free system with adjustable Si/Al ratios (2.15–2.87) were synthesized and compared to the commercial zeolite Y (HSZ-320NAA, Tosoh Co., Japan). We found that the as-synthesized and commercial zeolites with similar X-ray crystallinity and Si/Al ratios tend to show different susceptibility to removal of framework aluminium. Furthermore, our study indicates that increased extraction of framework aluminium atoms not always result in lower crystallinity. We attribute this behaviour to different distribution of Si(nAl) building units and structural defects as revealed by 29Si MAS-NMR, 27Al MAS-NMR and powder XRD analyses. We also found that the progressively increasing amount of extra-framework aluminium is inversely related with the Si/Al ratios of the dealuminated samples and contributes to higher catalytic activity. Finally, we evaluated the influence of X-ray crystallinity and Si/Al ratios on the catalytic performance of the as-synthesized and commercial samples.

A multiscale numerical investigation into the origin of the magnetoelectric effect in multiferroic composite materials was performed. Specifically, a well-known but unconfirmed mechanism for generating a macroscopic magnetoelectric effect through transmission of mechanical strain between the ferroelectric and ferromagnetic phases in an inhomogeneous microstructure was quantitatively established through multiscale finite element simulations. An asymptotic homogenization theory was employed for scale bridging between the macrostructure and the microstructure. Focusing first on a polycrystalline BaTiO3/Terfenol-D composite, the relation between the physical properties and the ferroelectric-phase content was analyzed. A uniform magnetic field was then applied to the macrostructure and the mechanical strain in the microstructure was investigated. The specific strain component exhibited an off-centered distribution when divided into ferroelectric and ferromagnetic phases. The simulation revealed that the macroscopic magnetoelectric effect is determined by two factors, the shift of the average strain from zero and the homogenized piezoelectric constant. The macroscopic magnetoelectric effect increases as the product of these two factors increases. This conclusion is applicable to other inhomogeneous structures and it can explain the trend in the magnitude of the magnetoelectric effect for a random polycrystalline structure, a layered polycrystalline structure, and a layered single-crystal structure. The findings are helpful for the functional design of multiferroic composite materials.