Imtiaz Mulla - Academia.edu (original) (raw)
Papers by Imtiaz Mulla
2012 1st International Symposium on Physics and Technology of Sensors (ISPTS-1), 2012
α-Fe2O3 nanorods have been prepared at low temperature by a facile surfactant free chemical route... more α-Fe2O3 nanorods have been prepared at low temperature by a facile surfactant free chemical route. The advantage of this method is good composition control and homogeneity. The products were characterized using various physicochemical characterization techniques such as X-ray Diffractometry, Raman spectroscopy, UV-Visible spectroscopy and Field Emission Scanning Electron Microscopy. These powders were further studied for their humidity sensing performance. The sensors exhibited quick responses for change in the humidity. The resistance systematically varies by four orders of magnitude on exposure to humidity from 20 to 90 % RH.
Journal of Materials Science: Materials in Electronics, 2016
In the present paper we have synthesized pristine and Sr doped SnO 2 in order to prepare a select... more In the present paper we have synthesized pristine and Sr doped SnO 2 in order to prepare a selective ethanol sensor with rapid response-recovery time and good repeatability. Pristine as well as Sr (2, 4 and 6 mol%) doped SnO 2 nanostructured powder was synthesized by using a facile co-precipitation method. The samples were characterized by TG-DTA, XRD, HR-TEM, SAED, FEG-SEM, SEM-EDAX, XPS, UV-Vis and FTIR spectroscopy techniques. The gas response performance of sensor towards ethanol, acetone, liquid petroleum gas and ammonia has been carried out. The results demonstrate that Sr doping in SnO 2 systematically decreases crystallite size, increases the porosity and hence enhances the gas response properties of pristine SnO 2 viz. lower operating temperature, higher ethanol response and better selectivity towards ethanol. The response and recovery time for 4 mol% Sr doped SnO 2 thick film sensor at the operating temperature of 300°C were 2 and 7 s, respectively.
AIP Conference Proceedings, 2013
ABSTRACT In the present investigation, we report facile synthesis method for the large area growt... more ABSTRACT In the present investigation, we report facile synthesis method for the large area growth of nanoflakesof β-Co(OH)2 thin film on SS substrate. The X-ray diffraction studies confimi the phase formation with brucite structure. The average thickness of the nanoflakes is about 100 nm. The electrochemical capacitive behavior of β-Co(OH)2 thin film is investigated by cyclic voltammetry in 1M KOH electrolyte and shows maximum specifie capacitance of 374 Fg-1.
Detection of hydrogen sulfide gas is important due to the environmental considerations and the he... more Detection of hydrogen sulfide gas is important due to the environmental considerations and the health hazards it posses. Sul-fides are known to be toxic for as a low as 100 ppm/air and hence sensors capable of detecting offensive sulfides are needed for the optimization of auto ventilation system of toilet or kitchen, dentistry etc. The present work talks about the different means of improving the sensitivity and selectivity of the tin oxide thin film towards hydrogen sulfide. The tin oxide thin film is modified with an overlayer of copper oxide nano-film deposited by the mono-layer protected copper nanoclusters and the newly developed liquid-liquid interface reaction technique (LLIRT). The other method involves incorporation of copper in the tin oxide matrix using spray pyrolysis. Modification of the thin film tin oxide surface by copper oxide nanofilm results in the enhancement of the sensitivity (s=100) and selectivity towards H2S as compared to the pure tin oxide (s=12) thin fil...
Polymer, 2008
In this paper, we compare two procedures for the synthesis of palladium (Pd)/polycarbonate (PC) n... more In this paper, we compare two procedures for the synthesis of palladium (Pd)/polycarbonate (PC) nanocomposites as well as their morphological, optical, thermal and electrical properties. Pd nanoclusters were produced by the reduction of palladium chloride using a variation of Brust's method. Discrete Pd nanoclusters of w15 nm size were formed in the absence of PC in the reaction mixture (ex situ method) while agglomeration of Pd nanoclusters was noticed in the presence of PC in the reaction mixture (in situ method). Fourier transform infrared spectroscopy (FTIR) suggests nanoparticlepolymer interactions and polymer conformational changes in the in situ nanocomposite films. Even after having the same Pd content, the ex situ nanocomposites films were found to transmit more light than the in situ nanocomposites. The glass transition temperature (T g), decreased by w16 C for both the ex situ and in situ samples. Thermogravimetric analysis (TGA) indicated that the presence of Pd nanoclusters significantly improved the thermal stability of the nanocomposites, as evidenced by the enhanced onset of degradation by w20 C and w40 C for the in situ and ex situ nanocomposites, respectively. The electrical conductivity measurement shows a dramatic difference between these nanocomposites with a significantly higher value for the in situ nanocomposite (resistivity ¼ 2.1 Â 10 5 Um) compared to the ex situ nanocomposite (resistivity ¼ 7.2 Â 10 13 Um).
Materials Chemistry and Physics, 2004
Tin oxide thin films were prepared by using a spray pyrolysis technique. It has been shown that t... more Tin oxide thin films were prepared by using a spray pyrolysis technique. It has been shown that the tin oxide thin film doped with thorium shows a high sensitivity towards trimethylamine (TMA) gas. It has been demonstrated that 1.18 wt.% thorium-doped tin oxide has a sensitivity of 2900 towards 800 vol. ppm TMA gas in air, while pure tin oxide has only a sensitivity of 5 at the operating temperature of 225 • C. Thorium stabilizes the tin oxide structure at lower deposition temperature, gives improved electrical characteristics and also enhances the sensitivity and selectivity towards TMA. The effect of surface coverage, morphology, oxidation state and amount of Th on the sensitivity and selectivity has been studied. The correlation of thorium doping in tin oxide at different deposition temperatures with morphology, improvement in the selectivity and sensitivity towards TMA is discussed.
Ceramics International, 2012
Nanocrystalline pristine and 0.5, 1.5 and 3.0 wt% Pd loaded SnO 2 were synthesized by a facile co... more Nanocrystalline pristine and 0.5, 1.5 and 3.0 wt% Pd loaded SnO 2 were synthesized by a facile co-precipitation route. These powders were screen-printed on alumina substrates to form thick films to investigate their gas sensing properties. The crystal structure and morphology of different samples were characterized by using X-ray diffraction, scanning electron microscopy and transmission electron microscopy techniques. The 3.0 wt% Pd:SnO 2 showed response of 85% toward 100 ppm of LPG at operating temperature of 250 8C with fast response (8 s) and quick recovery time (24 s). The high response toward LPG on Pd loading can be attributed to lowering of crystallite size (9 nm) as well as the role of Pd particles in exhibiting spill-over mechanism on the SnO 2 surface. Also selectivity of 3.0 wt% Pd:SnO 2 toward LPG was confirmed by measuring its response to other reducing gases like acetone (CH 3 COCH 3), ethanol (C 2 H 5 OH) and ammonia (NH 3) at optimum operating temperature.
Chemosensors
Herein, we describe the facile synthesis of spinel MgFe2O4 ferrite and its potential use as a gas... more Herein, we describe the facile synthesis of spinel MgFe2O4 ferrite and its potential use as a gas sensor using a straightforward and reliable sol–gel approach, i.e., the glycine-assisted auto-combustion route. The novelty in obtaining the sensing material via the auto-combustion route is its inherent simplicity and capability to produce the material at an industry scale. The said cost-effective process makes use of simple metal salts (Mg and Fe-nitrates) and glycine in an aqueous solution, which leads to the formation of spinel MgFe2O4 ferrite. A single-phase crystallinity with crystallite sizes ranging between 36 and 41 nm was observed for the synthesized materials using the X-ray diffraction (XRD) technique. The porous morphologies of the synthesized materials caused by auto-ignition during the combustion process were validated by the microscopic investigations. The EDS analysis confirmed the constituted elements such as Mg, Fe, and O, without any impurity peaks. The gas-sensing a...
Ceramics International, 2016
Journal of Porous Materials, 2020
We report a versatile epoxide assisted synthesis route of developing Ni/SnO 2 xerogels and their ... more We report a versatile epoxide assisted synthesis route of developing Ni/SnO 2 xerogels and their use as efficient H 2 S gas sensors. Instead of expensive, non-aqueous and complicated organometallic precursors, epoxide route utilizes easy to handle salts as precursors (tin and nickel nitrates, in the present case) and epoxide (propylene oxide, in the present case) as a gelation agent. The obtained Ni/SnO 2 xerogels with 1-4 mol% Ni doping, were analyzed using various physico-chemical techniques such as XRD, FE-SEM, TEM/HRTEM, EDAX, UV-Vis and FTIR spectroscopy. The developed nanomaterials showcase excellent physico-chemical as well as H 2 S gas sensing properties. Amongst the Ni doped SnO 2 xerogels, 3 mol% Ni/SnO 2 exhibited enhanced H 2 S response (from Ra/Rg value 5 to 11.5), and reduction in the operating temperature (from 325 to 275 °C). It showed a quick response of ~ 15 s and recovery within ~ 30 s. Almost 80.50% of its original efficiency after 60 days of shelf life, was exhibited with high stability. The developed route of Ni/SnO 2 xerogels proved its design for efficient H 2 S gas sensing, and have considerable potential for industrial use.
Journal of Nanoengineering and Nanomanufacturing, 2012
Journal of Materials Science: Materials in Electronics, 2015
2015 2nd International Symposium on Physics and Technology of Sensors (ISPTS), 2015
Herein present study, organic-inorganic hybrids based on WO3/PANI nanocomposites have been synthe... more Herein present study, organic-inorganic hybrids based on WO3/PANI nanocomposites have been synthesized at room temperature, by using oxidative polymerization. The as-synthesized products have been studied by using X-ray diffraction analysis, FE-SEM and optical characterization. The XRD analysis depicts peak broadening and the shift in peak position from standard values, which can be attributed to the formation of WO3 in the polyaniline matrix. Study of FE-SEM micrograph revealed that the cube-like WO3 particles get well dispersed in PANI matrix. WO3/PANI composite shows enhanced response and recovery time towards ammonia gas at room temperature.
Materials Letters, 2008
Ferroelectric CaBi 4 Ti 4 O 15 (CBT) powders were prepared for the first time from their respecti... more Ferroelectric CaBi 4 Ti 4 O 15 (CBT) powders were prepared for the first time from their respective hydroxides. Commercially purchased Ca(OH) 2 is mixed thoroughly with freshly prepared Bi(OH) 3 and Ti(OH) 4 in stoichiometric ratio and heated at different temperatures ranging from 100 to 600°C. The CBT phase found to be formed at 500°C by the X-ray diffraction studies. This is the lowest temperature so far reported in the literature for the formation of CBT phase. The advantage of this method is that it also avoids the formation of calcium carbonate phase during synthesis. The phase contents and lattice parameters were studied by the powder X-ray diffraction (XRD) method. The average particle size and morphology were studied by scanning electron microscopy (SEM) technique.
Polymer International, 2000
ABSTRACT
Journal of Power Sources, 2003
The use of self-assembled monolayers (SAM) of organic disulfide as novel cathode materials for hi... more The use of self-assembled monolayers (SAM) of organic disulfide as novel cathode materials for high specific energy, rechargeable, lithium batteries is demonstrated for the first time. The suitability of monolayer films of diphenyl disulfide (DDS) as cathode materials for facilitating reversible insertion and de-insertion of Li + ions is examined by means of cyclic voltammetry (CV), infra-red spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and charge-discharge measurements. The SAM-based cathodes on coupling with Li-metal anodes in 0.1 M LiClO 4 and tetrahydrofuran (THF) show good thermodynamic feasibility along with an open-circuit voltage of 2.9 V. The electrochemical capacity obtained is found, however, to fade during continuous cycling. This indicates a loss of electroactivity concomitant with the destruction of the monolayer functionalized cathode. The reasons for the coulombic efficiency of these rechargeable SAM-based cathodes are explained in terms of two different mechanistic modes of interaction of Li + ions with the monomolecular film.
Ceramics International, 2012
Undoped and Ni, Ce-doped nanocrystalline tin oxide were synthesized by co-precipitation route. Do... more Undoped and Ni, Ce-doped nanocrystalline tin oxide were synthesized by co-precipitation route. Doped as well as undoped SnO 2 compositions revealed single phase structure without any impurity. The lattice constant of SnO 2 increases and the grain size decreases with doping of Ni and Ce. The responses of the sensing elements are evaluated by measuring the resistance change upon exposure to various test gases such as liquid petroleum gas (LPG), acetone, ethanol and ammonia. In comparison to LPG, ethanol, and ammonia the response towards acetone vapor increases markedly on simultaneous doping of Ni and Ce. For acetone vapors with 500 ppm at 300 1C, the undoped SnO 2 shows 31% response, while with individual Ni or Ce doping it increases to 38 and 60%, respectively, however with simultaneous doping of Ni and Ce there is a significant enhancement up to 92%. The results of gas sensing measurements reveal that the thick films deposited on alumina substrates using screen printing technique give selectively a high response of (87%) with fast recovery ($1 min) towards 100 ppm acetone at 300 1C.
Journal of Alloys and Compounds, 2009
Polycrystalline magnesium ferrite (MgFe2O4) was prepared by the co-precipitation method. The synt... more Polycrystalline magnesium ferrite (MgFe2O4) was prepared by the co-precipitation method. The synthesized compound was characterized for their phase and morphology by X-ray diffraction and scanning electron microscopy, respectively. Conductance responses of the (MgFe2O4) were measured towards gases like hydrogen sulfide (H2S), liquefied petroleum gas (LPG), ethanol vapors (C2H5OH), SOx, H2, NOx, NH3, methanol, acetone and petrol. The gas sensing characterstics were obtained by measuring the sensitivity as a function of various controlling factors like operating temperatures and concentrations of gases. It was found that the sensor exhibited various responses towards these gases at different operating temperatures. Furthermore; the MgFe2O4 based sensor exhibited a fast response and a good recovery towards petrol at temperature 250°C. The results of the response towards petrol reveal that (MgFe2O4) synthesized by a simple co-precipitation method, would be a suitable material for the fabrication of the petrol sensor.
2012 1st International Symposium on Physics and Technology of Sensors (ISPTS-1), 2012
α-Fe2O3 nanorods have been prepared at low temperature by a facile surfactant free chemical route... more α-Fe2O3 nanorods have been prepared at low temperature by a facile surfactant free chemical route. The advantage of this method is good composition control and homogeneity. The products were characterized using various physicochemical characterization techniques such as X-ray Diffractometry, Raman spectroscopy, UV-Visible spectroscopy and Field Emission Scanning Electron Microscopy. These powders were further studied for their humidity sensing performance. The sensors exhibited quick responses for change in the humidity. The resistance systematically varies by four orders of magnitude on exposure to humidity from 20 to 90 % RH.
Journal of Materials Science: Materials in Electronics, 2016
In the present paper we have synthesized pristine and Sr doped SnO 2 in order to prepare a select... more In the present paper we have synthesized pristine and Sr doped SnO 2 in order to prepare a selective ethanol sensor with rapid response-recovery time and good repeatability. Pristine as well as Sr (2, 4 and 6 mol%) doped SnO 2 nanostructured powder was synthesized by using a facile co-precipitation method. The samples were characterized by TG-DTA, XRD, HR-TEM, SAED, FEG-SEM, SEM-EDAX, XPS, UV-Vis and FTIR spectroscopy techniques. The gas response performance of sensor towards ethanol, acetone, liquid petroleum gas and ammonia has been carried out. The results demonstrate that Sr doping in SnO 2 systematically decreases crystallite size, increases the porosity and hence enhances the gas response properties of pristine SnO 2 viz. lower operating temperature, higher ethanol response and better selectivity towards ethanol. The response and recovery time for 4 mol% Sr doped SnO 2 thick film sensor at the operating temperature of 300°C were 2 and 7 s, respectively.
AIP Conference Proceedings, 2013
ABSTRACT In the present investigation, we report facile synthesis method for the large area growt... more ABSTRACT In the present investigation, we report facile synthesis method for the large area growth of nanoflakesof β-Co(OH)2 thin film on SS substrate. The X-ray diffraction studies confimi the phase formation with brucite structure. The average thickness of the nanoflakes is about 100 nm. The electrochemical capacitive behavior of β-Co(OH)2 thin film is investigated by cyclic voltammetry in 1M KOH electrolyte and shows maximum specifie capacitance of 374 Fg-1.
Detection of hydrogen sulfide gas is important due to the environmental considerations and the he... more Detection of hydrogen sulfide gas is important due to the environmental considerations and the health hazards it posses. Sul-fides are known to be toxic for as a low as 100 ppm/air and hence sensors capable of detecting offensive sulfides are needed for the optimization of auto ventilation system of toilet or kitchen, dentistry etc. The present work talks about the different means of improving the sensitivity and selectivity of the tin oxide thin film towards hydrogen sulfide. The tin oxide thin film is modified with an overlayer of copper oxide nano-film deposited by the mono-layer protected copper nanoclusters and the newly developed liquid-liquid interface reaction technique (LLIRT). The other method involves incorporation of copper in the tin oxide matrix using spray pyrolysis. Modification of the thin film tin oxide surface by copper oxide nanofilm results in the enhancement of the sensitivity (s=100) and selectivity towards H2S as compared to the pure tin oxide (s=12) thin fil...
Polymer, 2008
In this paper, we compare two procedures for the synthesis of palladium (Pd)/polycarbonate (PC) n... more In this paper, we compare two procedures for the synthesis of palladium (Pd)/polycarbonate (PC) nanocomposites as well as their morphological, optical, thermal and electrical properties. Pd nanoclusters were produced by the reduction of palladium chloride using a variation of Brust's method. Discrete Pd nanoclusters of w15 nm size were formed in the absence of PC in the reaction mixture (ex situ method) while agglomeration of Pd nanoclusters was noticed in the presence of PC in the reaction mixture (in situ method). Fourier transform infrared spectroscopy (FTIR) suggests nanoparticlepolymer interactions and polymer conformational changes in the in situ nanocomposite films. Even after having the same Pd content, the ex situ nanocomposites films were found to transmit more light than the in situ nanocomposites. The glass transition temperature (T g), decreased by w16 C for both the ex situ and in situ samples. Thermogravimetric analysis (TGA) indicated that the presence of Pd nanoclusters significantly improved the thermal stability of the nanocomposites, as evidenced by the enhanced onset of degradation by w20 C and w40 C for the in situ and ex situ nanocomposites, respectively. The electrical conductivity measurement shows a dramatic difference between these nanocomposites with a significantly higher value for the in situ nanocomposite (resistivity ¼ 2.1 Â 10 5 Um) compared to the ex situ nanocomposite (resistivity ¼ 7.2 Â 10 13 Um).
Materials Chemistry and Physics, 2004
Tin oxide thin films were prepared by using a spray pyrolysis technique. It has been shown that t... more Tin oxide thin films were prepared by using a spray pyrolysis technique. It has been shown that the tin oxide thin film doped with thorium shows a high sensitivity towards trimethylamine (TMA) gas. It has been demonstrated that 1.18 wt.% thorium-doped tin oxide has a sensitivity of 2900 towards 800 vol. ppm TMA gas in air, while pure tin oxide has only a sensitivity of 5 at the operating temperature of 225 • C. Thorium stabilizes the tin oxide structure at lower deposition temperature, gives improved electrical characteristics and also enhances the sensitivity and selectivity towards TMA. The effect of surface coverage, morphology, oxidation state and amount of Th on the sensitivity and selectivity has been studied. The correlation of thorium doping in tin oxide at different deposition temperatures with morphology, improvement in the selectivity and sensitivity towards TMA is discussed.
Ceramics International, 2012
Nanocrystalline pristine and 0.5, 1.5 and 3.0 wt% Pd loaded SnO 2 were synthesized by a facile co... more Nanocrystalline pristine and 0.5, 1.5 and 3.0 wt% Pd loaded SnO 2 were synthesized by a facile co-precipitation route. These powders were screen-printed on alumina substrates to form thick films to investigate their gas sensing properties. The crystal structure and morphology of different samples were characterized by using X-ray diffraction, scanning electron microscopy and transmission electron microscopy techniques. The 3.0 wt% Pd:SnO 2 showed response of 85% toward 100 ppm of LPG at operating temperature of 250 8C with fast response (8 s) and quick recovery time (24 s). The high response toward LPG on Pd loading can be attributed to lowering of crystallite size (9 nm) as well as the role of Pd particles in exhibiting spill-over mechanism on the SnO 2 surface. Also selectivity of 3.0 wt% Pd:SnO 2 toward LPG was confirmed by measuring its response to other reducing gases like acetone (CH 3 COCH 3), ethanol (C 2 H 5 OH) and ammonia (NH 3) at optimum operating temperature.
Chemosensors
Herein, we describe the facile synthesis of spinel MgFe2O4 ferrite and its potential use as a gas... more Herein, we describe the facile synthesis of spinel MgFe2O4 ferrite and its potential use as a gas sensor using a straightforward and reliable sol–gel approach, i.e., the glycine-assisted auto-combustion route. The novelty in obtaining the sensing material via the auto-combustion route is its inherent simplicity and capability to produce the material at an industry scale. The said cost-effective process makes use of simple metal salts (Mg and Fe-nitrates) and glycine in an aqueous solution, which leads to the formation of spinel MgFe2O4 ferrite. A single-phase crystallinity with crystallite sizes ranging between 36 and 41 nm was observed for the synthesized materials using the X-ray diffraction (XRD) technique. The porous morphologies of the synthesized materials caused by auto-ignition during the combustion process were validated by the microscopic investigations. The EDS analysis confirmed the constituted elements such as Mg, Fe, and O, without any impurity peaks. The gas-sensing a...
Ceramics International, 2016
Journal of Porous Materials, 2020
We report a versatile epoxide assisted synthesis route of developing Ni/SnO 2 xerogels and their ... more We report a versatile epoxide assisted synthesis route of developing Ni/SnO 2 xerogels and their use as efficient H 2 S gas sensors. Instead of expensive, non-aqueous and complicated organometallic precursors, epoxide route utilizes easy to handle salts as precursors (tin and nickel nitrates, in the present case) and epoxide (propylene oxide, in the present case) as a gelation agent. The obtained Ni/SnO 2 xerogels with 1-4 mol% Ni doping, were analyzed using various physico-chemical techniques such as XRD, FE-SEM, TEM/HRTEM, EDAX, UV-Vis and FTIR spectroscopy. The developed nanomaterials showcase excellent physico-chemical as well as H 2 S gas sensing properties. Amongst the Ni doped SnO 2 xerogels, 3 mol% Ni/SnO 2 exhibited enhanced H 2 S response (from Ra/Rg value 5 to 11.5), and reduction in the operating temperature (from 325 to 275 °C). It showed a quick response of ~ 15 s and recovery within ~ 30 s. Almost 80.50% of its original efficiency after 60 days of shelf life, was exhibited with high stability. The developed route of Ni/SnO 2 xerogels proved its design for efficient H 2 S gas sensing, and have considerable potential for industrial use.
Journal of Nanoengineering and Nanomanufacturing, 2012
Journal of Materials Science: Materials in Electronics, 2015
2015 2nd International Symposium on Physics and Technology of Sensors (ISPTS), 2015
Herein present study, organic-inorganic hybrids based on WO3/PANI nanocomposites have been synthe... more Herein present study, organic-inorganic hybrids based on WO3/PANI nanocomposites have been synthesized at room temperature, by using oxidative polymerization. The as-synthesized products have been studied by using X-ray diffraction analysis, FE-SEM and optical characterization. The XRD analysis depicts peak broadening and the shift in peak position from standard values, which can be attributed to the formation of WO3 in the polyaniline matrix. Study of FE-SEM micrograph revealed that the cube-like WO3 particles get well dispersed in PANI matrix. WO3/PANI composite shows enhanced response and recovery time towards ammonia gas at room temperature.
Materials Letters, 2008
Ferroelectric CaBi 4 Ti 4 O 15 (CBT) powders were prepared for the first time from their respecti... more Ferroelectric CaBi 4 Ti 4 O 15 (CBT) powders were prepared for the first time from their respective hydroxides. Commercially purchased Ca(OH) 2 is mixed thoroughly with freshly prepared Bi(OH) 3 and Ti(OH) 4 in stoichiometric ratio and heated at different temperatures ranging from 100 to 600°C. The CBT phase found to be formed at 500°C by the X-ray diffraction studies. This is the lowest temperature so far reported in the literature for the formation of CBT phase. The advantage of this method is that it also avoids the formation of calcium carbonate phase during synthesis. The phase contents and lattice parameters were studied by the powder X-ray diffraction (XRD) method. The average particle size and morphology were studied by scanning electron microscopy (SEM) technique.
Polymer International, 2000
ABSTRACT
Journal of Power Sources, 2003
The use of self-assembled monolayers (SAM) of organic disulfide as novel cathode materials for hi... more The use of self-assembled monolayers (SAM) of organic disulfide as novel cathode materials for high specific energy, rechargeable, lithium batteries is demonstrated for the first time. The suitability of monolayer films of diphenyl disulfide (DDS) as cathode materials for facilitating reversible insertion and de-insertion of Li + ions is examined by means of cyclic voltammetry (CV), infra-red spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and charge-discharge measurements. The SAM-based cathodes on coupling with Li-metal anodes in 0.1 M LiClO 4 and tetrahydrofuran (THF) show good thermodynamic feasibility along with an open-circuit voltage of 2.9 V. The electrochemical capacity obtained is found, however, to fade during continuous cycling. This indicates a loss of electroactivity concomitant with the destruction of the monolayer functionalized cathode. The reasons for the coulombic efficiency of these rechargeable SAM-based cathodes are explained in terms of two different mechanistic modes of interaction of Li + ions with the monomolecular film.
Ceramics International, 2012
Undoped and Ni, Ce-doped nanocrystalline tin oxide were synthesized by co-precipitation route. Do... more Undoped and Ni, Ce-doped nanocrystalline tin oxide were synthesized by co-precipitation route. Doped as well as undoped SnO 2 compositions revealed single phase structure without any impurity. The lattice constant of SnO 2 increases and the grain size decreases with doping of Ni and Ce. The responses of the sensing elements are evaluated by measuring the resistance change upon exposure to various test gases such as liquid petroleum gas (LPG), acetone, ethanol and ammonia. In comparison to LPG, ethanol, and ammonia the response towards acetone vapor increases markedly on simultaneous doping of Ni and Ce. For acetone vapors with 500 ppm at 300 1C, the undoped SnO 2 shows 31% response, while with individual Ni or Ce doping it increases to 38 and 60%, respectively, however with simultaneous doping of Ni and Ce there is a significant enhancement up to 92%. The results of gas sensing measurements reveal that the thick films deposited on alumina substrates using screen printing technique give selectively a high response of (87%) with fast recovery ($1 min) towards 100 ppm acetone at 300 1C.
Journal of Alloys and Compounds, 2009
Polycrystalline magnesium ferrite (MgFe2O4) was prepared by the co-precipitation method. The synt... more Polycrystalline magnesium ferrite (MgFe2O4) was prepared by the co-precipitation method. The synthesized compound was characterized for their phase and morphology by X-ray diffraction and scanning electron microscopy, respectively. Conductance responses of the (MgFe2O4) were measured towards gases like hydrogen sulfide (H2S), liquefied petroleum gas (LPG), ethanol vapors (C2H5OH), SOx, H2, NOx, NH3, methanol, acetone and petrol. The gas sensing characterstics were obtained by measuring the sensitivity as a function of various controlling factors like operating temperatures and concentrations of gases. It was found that the sensor exhibited various responses towards these gases at different operating temperatures. Furthermore; the MgFe2O4 based sensor exhibited a fast response and a good recovery towards petrol at temperature 250°C. The results of the response towards petrol reveal that (MgFe2O4) synthesized by a simple co-precipitation method, would be a suitable material for the fabrication of the petrol sensor.