Enhanced response of WO3 thin film through Ag loading towards room temperature hydrogen gas sensor.

This study investigates the enhancement of hydrogen gas-sensing performance by introducing silver (Ag) nanoparticles onto tungsten trioxide (WO3) thin films. Herein, the WO3 thin films are deposited onto SiO2/Si substrates using a sputtering technique and Ag nanoparticles are loaded onto the WO3 surface through a spin coating technique. To evaluate the sensing performance of a hydrogen gas, interdigitated titanium (Ti) electrodes are deposited onto the Ag:WO3 layer. Structural, chemical, and morphological analyses are conducted for both pristine WO3 and Ag:WO3 thin films, followed by the investigation of gas-sensing performance by varying hydrogen gas concentrations from 100 ppm to 300 ppm and operating temperatures between 30 °C and 300 °C. The obtained results demonstrate that Ag:WO3 thin films exhibit a notably enhanced response of 5.08% when exposed to a concentration of 100 ppm of hydrogen gas at room temperature, compared to the pristine WO3 of 3.40%. The fabricated Ag:WO3 sensor exhibits a response time of 3.0 s, a recovery time of 4.5 s, and also demonstrates excellent stability over 45 days period. Finally, with the superior sensitivity and fast response time, the fabricated Ti/Ag:WO3/Ti hydrogen gas sensor test-device can be a potential for improvement of safety from both industrial and environmental perspectives.

Biosynthesis of silver nanoparticles using Momordica charantia leaf broth: Evaluation of their innate antimicrobial and catalytic activities.

Silver nanoparticles (AgNPs) were prepared through green route with the aid of Momordica charantia leaf extract as both reductant and stabilizer. X-ray diffraction pattern (XRD) and selected area electron diffraction (SAED) fringes revealed the structure of AgNPs as face centered cubic (fcc). Morphological studies elucidate the nearly spherical AgNPs formation with particle size in nanoscale. Biosynthesized AgNPs were found to be photoluminescent and UV-Vis absorption spectra showed one surface plasmon resonance peak (SPR) at 424nm attesting the spherical nanoparticles formation. XPS study provides the surface chemical nature and oxidation state of the synthesized nanoparticles. FTIR spectra ascertain the reduction and capping nature of phytoconstituents of leaf extract in AgNPs synthesis. Further, these AgNPs showed effective antimicrobial activity against tested pathogens and thus applicable as potent antimicrobial agent. In addition, the synthesized AgNPs were observed to have an excellent catalytic activity on the reduction of methylene blue by M. charantia which was confirmed by the decrement in maximum absorbance values of methylene blue with respect to time and is ascribed to electron relay effect.

Biogenic nano-scale silver particles by Tephrosia purpurea leaf extract and their inborn antimicrobial activity.

In this paper we report the green synthesis of silver nanoparticles (Ag NPs) using Tephrosia purpurea leaf extract. The biomolecules present in the leaf extract are responsible for the formation of Ag NPs and they found to play dual role of both reducing as well as capping agents. The high crystallinity of Ag NPs is evident from bright circular spot array of SAED pattern and diffraction peaks in XRD profile. The synthesized Ag NPs are found to be nearly spherical ones with size approximately ∼20 nm. FTIR spectrum evidences the presence of different functional groups of biomolecules participated in encapsulating Ag NPs and the possible mechanism of Ag NPs formation was also suggested. Appearance of yellow color and surface plasmon resonance (SPR) peak at 425 nm confirms the Ag NPs formation. PL spectra showed decrement in luminescence intensity at higher excitation wavelengths. Antimicrobial activity of Ag NPs showed better inhibitory activity towards Pseudomonas spp. and Penicillium spp. compared to other test pathogens using standard Kirby-Bauer disc diffusion assay.