Search

Your search keyword '"Gupta, S. K."' showing total 3 results
3 results on '"Gupta, S. K."'

1. H2S DETECTION BY CuO NANOWIRES AT ROOM TEMPERATURE.

Author

KAUR, MANMEET, GANAPATHI, KAILASA, DATTA, NIYANTA, MUTHE, K. P., and GUPTA, S. K.

Subjects
*HYDROGEN sulfide, *COPPER oxide, *NANOWIRES, *TEMPERATURE effect, *GAS detectors, *METAL foils, *CRYSTAL growth
Abstract

Room temperature gas sensing properties of CuO nanowires synthesized by thermal oxidation of copper foils was studied in different configurations: (i) isolated nanowires aligned between two electrodes, (ii) as grown CuO foil consisting of nanowires and (iii) CuO nanowire films. Sensors were studied for response to different gases. Different sensors showed qualitatively different response on exposure to H2S. Isolated nanowires showed high sensitivity, (~200% for 10 ppm of gas) and fast response (30 s) and recovery times (60 s). In these samples, the resistance mainly decreased on exposure to H2S (though a small initial increase was observed). In CuO foils, resistance increased for low concentrations (5-10 ppm) but decreased at high concentrations. In the case of CuO nanowire films, resistance only increased on exposure of H2S (upto 400 ppm). Since CuO is a p-type semiconductor, on exposure to H2S an increase in resistance is expected due to oxygen adsorption related process. Decrease in resistance in some of the sensors was understood in terms of reaction of CuO with H2S resulting in the formation of CuS. [ABSTRACT FROM AUTHOR]

Published
2011
Full Text
View/download PDF

2. ZnO Nanowires As H2S Sensor.

Author

Ramgir, N. S., Rikka, V., Kaur, M., Ganapathi, S. Kailasa, Mishra, S. K., Datta, N., Aswal, D. K., Gupta, S. K., and Yakhmi, J. V.

Subjects
*ZINC oxide, *NANOWIRES, *DETECTORS, *HYDROGEN sulfide, *CRYSTAL growth, *PHOTOLUMINESCENCE, *NANOPARTICLES, *SEMICONDUCTORS
Abstract

Hydrothermal growth of ZnO nanowires were performed using ZnO nanoparticles as a seed layer. The growth was found to depend strongly on the reaction duration. These nanowires detected H2S with faster response and recovery time of 13 and 78 s, respectively towards 20 ppm at 350° C. The lowest detection limit was improved to 0.6 ppm upon annealing in O2 flow of 50 sccm. The response time was further improved to just 6 s towards 20 ppm of H2S at 350° C. The enhanced response characteristics have been attributed to the high surface area to volume ratio of nanowires. Photoluminescence (PL) studies showed increase in the green emission related to defect states in ZnO. This is also expected to contribute for the improved sensing characteristics. [ABSTRACT FROM AUTHOR]

Published
2010
Full Text
View/download PDF

3. Kelvin probe studies of H2S exposed CuO:ZnO nanowires random networks.

Author

Datta, Niyanta, Ramgir, Niranjan, Kaur, Manmeet, Ganpathi, Kailasa, Debnath, A. K., Aswal, D. K., and Gupta, S. K.

Subjects
*KELVIN'S circulation theorem, *HYDROGEN sulfide, *COPPER oxide, *ZINC oxide, *NANOWIRES, *ELECTRON affinity
Abstract

The Kelvin Probe (KP) studies have been carried out on CuO:ZnO nanowires random networks before and after H2S exposure. The results show that on exposure to H2S, the work function of the CuO:ZnO NWs increases by 200 meV. Using conductance and KP data, both the components of work function i.e. band bending and electron affinity has been obtained. It was observed that the affinity values changed substantially with H2S gas exposure. [ABSTRACT FROM AUTHOR]

Published
2013
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results