Faculty Publications
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Item Room-temperature detection of ammonia and formaldehyde gases by La xBa1?xSnO3?? (x = 0 and 0.05) screen printed sensors: effect of ceria and ruthenate sensitization(Springer Science and Business Media Deutschland GmbH, 2021) Manjunath, G.; Vardhan, R.V.; Praveen, L.L.; Pothukanuri, P.; Mandal, S.In the present work, gas sensing properties of the screen printed ceria and ruthenate-sensitized BaSnO3 (BSO) with La doping heterostructure sensors towards the detection of ammonia and formaldehyde gases at room temperature were studied. Adhered, porous screen printed films with different morphologies were obtained by depositing the LaxBa1?xSnO3?? (x = 0 and 0.05) powder particles prepared by the polymerized complex method. Ceria and ruthenate sensitization for screen printed LaxBa1?xSnO3?? (x = 0.05) film was processed through dip-coating in the 0.03 M aqueous solution of CeCl3 and RuCl3, respectively. La-doped BaSnO3 (LBSO) sensor with smaller crystallites, needle-like morphology and high concentration of oxygen vacancies exhibited superior gas response of 65 and 29 towards 50 ppm of ammonia and formaldehyde gases, respectively. Superabundant sensitization of ceria and ruthenate reduced the oxygen vacancy and structural open porosity in the LBSO sensor; therefore, the ammonia gas response was decreased from 65 to 14 and 3, respectively, whereas the formaldehyde gas response was reduced to less than 1/6th times the LBSO sensor. Limit of detection of LBSO sensors was estimated to be ~ 1 and ~ 2 ppm against ammonia and formaldehyde, respectively. The presence of fluorite structured phase ceria with high oxygen atoms storage capacity facilitates the rapid oxidization of analyte gases and caused the expeditious response (75 s) and recovery (60 s) in CeOx-sensitized LBSO sensor. This study might give a new insight into the development of doped and sensitized BSO-based gas sensors operating at ambient conditions. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.Item Ammonia gas detection by solution combustion-processed pristine & Ti-doped ZnO transparent films: a reverse effect of doping on gas response(Springer, 2023) Vardhan, R.V.; Manjunath, G.; Pothukanuri, P.; Mandal, S.In this contribution, pure, polycrystalline wurtzite crystal structured, spin-coated pristine ZnO and Ti-doped (1, 2, and 3 wt%) ZnO transparent films were accomplished at 400 °C through a facile solution combustion synthesis method. Crystallinity, roughness, and porosity in the pristine film were relatively higher than in the doped films. The demonstrated films were transparent, with ~ 70 to 90% in the visible region. The room temperature detection of ammonia (NH3) gas (25–100 ppm) was recognized in all the films. The pristine film revealed a superior gas response at every concentration of NH3 gas in contrast to all the doped films; it is probably due to comparatively high crystallinity, porosity, more oxygen vacancy concentration (1.788), and high fraction of adsorbed oxygen (20.55%). The film exhibited the highest gas response of 34.7 at 100 ppm of NH3 gas and a limit of detection of ~ 10.7 ppm with superior selectivity towards NH3 gas. Although doping enhanced the transparency but diminished the NH3 gas response due to the combined effect of deterioration in the mentioned properties achieved in pristine film. © 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Item Tracing of Ammonia Gas by Solution-Combustion-Derived Pristine and Nb-Doped TiO2 Films: Beneficial Impact of Crystallinity and Adsorbed Oxygen on the Gas Response(Springer, 2023) Vardhan, R.V.; Manjunath, G.; Pothukanuri, P.; Mandal, S.The current work delivers room-temperature ammonia (NH3) gas-detectable pristine, Nb-doped TiO2 air- and vacuum-annealed films obtained through the solution-combustion process. Polycrystalline anatase crystal structured films without any dopant oxide phases were processed at 400°C on glass substrates. The crystallinity was higher in pristine films than in doped films; the morphological features were similar in all the films. The films were > 50% transparent, and the estimated optical energy band gap was greater in doped films than in pristine films. All the films detected NH3 gas (25 ppm to 100 ppm) at room temperature, and the gas response was highly dependent on the crystallinity and relative area fraction of adsorbed oxygen (% of OA). The vacuum-annealed pristine film exhibited a better gas response than the other films at all NH3 gas concentrations due to high crystallinity and % of OA (10.15%). The film demonstrated maximum gas response of ~16 towards 100 ppm of NH3 gas and displayed good selectivity. Even though the doping reduced the crystallite size from ~17 nm to ~9 nm, it also diminished the crystallinity of the films, which significantly impacted the deterioration of their gas response. © 2023, The Minerals, Metals & Materials Society.Item Detection of ethanol gas at room temperature by In2O3-based screen-printed films fabricated through particle-free aqueous solution combustible inks(Institute of Physics, 2024) Vardhan, R.V.; Praveen, L.L.; Manjunath, G.; Pothukanuri, P.; Seikh, A.H.; Alnaser, I.A.; Mandal, S.The current work investigates the room temperature ethanol gas detection capabilities of pristine, Sn-doped, Zn-doped, Sn & Zn co-doped In2O3-based screen-printed films, fabricated using particle-free aqueous solution combustible inks on glass substrates. The fabricated films were pure, polycrystalline with cubic bixbyite crystal structure, porous, and transparent (∼75 to 95%) in the visible range. Relatively high surface roughness was detected in pristine film than in doped films. Ethanol gas was detected by all the films at room temperature. Among all, the pristine film showed a relatively greater gas response at all concentrations of ethanol gas ranging from 25 ppm to 100 ppm. This superior gas response was attributed to comparatively greater oxygen vacancy concentration (OV/OL), relative area fraction of surface adsorbed oxygen (% of OA), and high surface roughness with porosity. The maximum ethanol gas response attained was ∼17 at 100 ppm concentration by the pristine film, which also demonstrated high selectivity to ethanol gas. © 2024 The Author(s). Published by IOP Publishing Ltd.