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Papers by Ravindranathan Thampi
The Journal of Physical Chemistry, May 1, 1989
... via Polytungstate Dispersed on Titania M. Gratzel, KR Thampi, and J. Kiwi* Institut de chimie... more ... via Polytungstate Dispersed on Titania M. Gratzel, KR Thampi, and J. Kiwi* Institut de chimie physique, Ecole Polytechnique FZdPrale, CH-101.5 Lausanne, Switzerland (Received: February 10, 1988: In Final Form: September 21, 1988) ... (b) Ward, M. D., Brazdil, J. F., Grasselli. ...
Zenodo (CERN European Organization for Nuclear Research), Dec 31, 1983
The Ru-RuOx/TiO2 catalyst has been shown to be able to produce methane from hydrogen and carbon d... more The Ru-RuOx/TiO2 catalyst has been shown to be able to produce methane from hydrogen and carbon dioxide at room temperature and atmospheric pressure at reasonably high rates (TOF: 10-6 at 25C and 10-4 at 90C). The best results were obtained using the P25 support (Degussa 80% anatase and 20% rutile) in the 55-60 m2/g surface area range. The optimal loading for the metal is 3.8% Ru metal.We found that in the most active catalysts, the metal (>90%) is selectively loaded on the rutile crystallites. This distribution shows up clearly in a 500C reduced sample (fig.l) in which the size of the metal particles has increased.
23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain, Nov 1, 2008
Research in the field of dye sensitized solar cells is presently focused on the development and s... more Research in the field of dye sensitized solar cells is presently focused on the development and study of new and improved cell components with the twin aims of simultaneously increasing both the energy conversion efficiency and the device stability. To achieve these objectives, new sensitizers with increased molar extinction coefficients, and new ionic liquids and performance enhancing electrolyte additives have been synthesized and tested. Together with the commercially available TiO2 pastes of high performance, DSC today reached light-to-electricity conversion efficiencies of 11.3% under full AM1.5 global sunlight illumination. These new dyes and oxide materials along with low volatile electrolyte formulations are used to make DSC exhibiting excellent device stability at 60 °C in light. New high molar extinction coefficient dyes enable to decrease the mesoporous oxide layer thickness considerably to < 10 microns. This will pave way to build highly efficient tandem DSC devices, where the lower cells would selectively harvest the IR spectral region of sunlight.
International Journal of Hydrogen Energy, Sep 1, 2017
ChemInform, Aug 23, 2010
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Eurasian Chemico-Technological Journal, Sep 21, 2016
Journal of Catalysis, Oct 1, 1992
At least six C-O stretch vibrational bands at around 2,142, 2,132, 2,085, 2,050, 1,995, and 1,950... more At least six C-O stretch vibrational bands at around 2,142, 2,132, 2,085, 2,050, 1,995, and 1,950 cm{sup {minus}1} were detected in the room temperature adsorption of both CO and CO + H{sub 2} over titania-supported partially reduced ruthenium. These bands were identifiable with the reported multicarbonyl and the linear-bonded monocarbonyl species and indicate that the different oxidation states of ruthenium serve as independent CO chemisorption sites which may coexist on a real catalyst surface at a particular temperature. The effect of exposure temperature and that of the postexposure thermal annealing on CO vibrational bands suggest that the multicarbonyl species transform progressively to monocarbonyl forms which are in turn identified as precursors to the methylene groups in the presence of hydrogen. Though the presence of hydrogen had no apparent effect on the shape and the frequency of different C-O stretch bands, CO + H{sub 2} interaction at temperatures above 400 K gave rise to hydrocarbon structures consisting of a chain of methylene groups. The presence of these hydrocarbon chains blocking binding sites responsible for v{sub CO} = 2,050 cm{sup {minus}1} monocarbonyl species. The promotional effect of oxidized ruthenium and the role of oxygenated surface complexes in CO methanation are discussed inmore » light of the present results.« less
Elsevier eBooks, 1989
Partially-reduced ruthenium dioxide on titania is an active and selective catalyst for methane fo... more Partially-reduced ruthenium dioxide on titania is an active and selective catalyst for methane formation from carbon dioxide, already at temperatures below 100 C. Results from catalytic screening together with characterization by electron microscopy indicate that the TiO 2 support (Degussa P25 in particular) plays a major role in stabilizing metallic ruthenium in highly-dispersed form (d 10-30 A), provided care is taken in the RuO 2 deposition step. Chemisorption of H 2 and CO 2 has revealed a strong g coadsorption synergy together with extensive hydrogen spillover. Diffuse Reflectance Infrared Fourier Transform (DRIFT) Spectroscopy in situ has provided confirmatory evidence of the latter, and shown that CO, believed to arise from the reverse water-gas shift reaction accumulates on the metal causing catalyst deactivation. Heating above 100 facilitates the Boudouard disproportionation reaction and the activity is regenerated. Implications for the mechanism of CO 2 hydrogenation are briefly discussed.
CHIMIA
With the solid oxide-fuel cell, a technology exploiting ionic conductivity in electroceramic mate... more With the solid oxide-fuel cell, a technology exploiting ionic conductivity in electroceramic materials, small-scale co-generation plants for combined production of heat and electricity can achieve clean high-efficiency operation. However, with thermal activation of the cell chemistry, extremely high operating temperatures, about 1000°, are required, conditions incompatible with long term reliability using conventional structural materials. Lower-temperature operation depends decisively on the application of electrocatalysis at interfaces to the ceramic electrolyte.
Studies in Surface Science and Catalysis, 1993
ABSTRACT
Proceedings, annual meeting, Electron Microscopy Society of America, 1990
The Ru-RuOx/TiO2 catalyst has been shown to be able to produce methane from hydrogen and carbon d... more The Ru-RuOx/TiO2 catalyst has been shown to be able to produce methane from hydrogen and carbon dioxide at room temperature and atmospheric pressure at reasonably high rates (TOF: 10-6 at 25C and 10-4 at 90C). The best results were obtained using the P25 support (Degussa 80% anatase and 20% rutile) in the 55-60 m2/g surface area range. The optimal loading for the metal is 3.8% Ru metal.We found that in the most active catalysts, the metal (>90%) is selectively loaded on the rutile crystallites. This distribution shows up clearly in a 500C reduced sample (fig.l) in which the size of the metal particles has increased.
The Journal of Physical Chemistry, May 1, 1989
... via Polytungstate Dispersed on Titania M. Gratzel, KR Thampi, and J. Kiwi* Institut de chimie... more ... via Polytungstate Dispersed on Titania M. Gratzel, KR Thampi, and J. Kiwi* Institut de chimie physique, Ecole Polytechnique FZdPrale, CH-101.5 Lausanne, Switzerland (Received: February 10, 1988: In Final Form: September 21, 1988) ... (b) Ward, M. D., Brazdil, J. F., Grasselli. ...
Zenodo (CERN European Organization for Nuclear Research), Dec 31, 1983
The Ru-RuOx/TiO2 catalyst has been shown to be able to produce methane from hydrogen and carbon d... more The Ru-RuOx/TiO2 catalyst has been shown to be able to produce methane from hydrogen and carbon dioxide at room temperature and atmospheric pressure at reasonably high rates (TOF: 10-6 at 25C and 10-4 at 90C). The best results were obtained using the P25 support (Degussa 80% anatase and 20% rutile) in the 55-60 m2/g surface area range. The optimal loading for the metal is 3.8% Ru metal.We found that in the most active catalysts, the metal (&amp;amp;gt;90%) is selectively loaded on the rutile crystallites. This distribution shows up clearly in a 500C reduced sample (fig.l) in which the size of the metal particles has increased.
23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain, Nov 1, 2008
Research in the field of dye sensitized solar cells is presently focused on the development and s... more Research in the field of dye sensitized solar cells is presently focused on the development and study of new and improved cell components with the twin aims of simultaneously increasing both the energy conversion efficiency and the device stability. To achieve these objectives, new sensitizers with increased molar extinction coefficients, and new ionic liquids and performance enhancing electrolyte additives have been synthesized and tested. Together with the commercially available TiO2 pastes of high performance, DSC today reached light-to-electricity conversion efficiencies of 11.3% under full AM1.5 global sunlight illumination. These new dyes and oxide materials along with low volatile electrolyte formulations are used to make DSC exhibiting excellent device stability at 60 °C in light. New high molar extinction coefficient dyes enable to decrease the mesoporous oxide layer thickness considerably to < 10 microns. This will pave way to build highly efficient tandem DSC devices, where the lower cells would selectively harvest the IR spectral region of sunlight.
International Journal of Hydrogen Energy, Sep 1, 2017
ChemInform, Aug 23, 2010
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Eurasian Chemico-Technological Journal, Sep 21, 2016
Journal of Catalysis, Oct 1, 1992
At least six C-O stretch vibrational bands at around 2,142, 2,132, 2,085, 2,050, 1,995, and 1,950... more At least six C-O stretch vibrational bands at around 2,142, 2,132, 2,085, 2,050, 1,995, and 1,950 cm{sup {minus}1} were detected in the room temperature adsorption of both CO and CO + H{sub 2} over titania-supported partially reduced ruthenium. These bands were identifiable with the reported multicarbonyl and the linear-bonded monocarbonyl species and indicate that the different oxidation states of ruthenium serve as independent CO chemisorption sites which may coexist on a real catalyst surface at a particular temperature. The effect of exposure temperature and that of the postexposure thermal annealing on CO vibrational bands suggest that the multicarbonyl species transform progressively to monocarbonyl forms which are in turn identified as precursors to the methylene groups in the presence of hydrogen. Though the presence of hydrogen had no apparent effect on the shape and the frequency of different C-O stretch bands, CO + H{sub 2} interaction at temperatures above 400 K gave rise to hydrocarbon structures consisting of a chain of methylene groups. The presence of these hydrocarbon chains blocking binding sites responsible for v{sub CO} = 2,050 cm{sup {minus}1} monocarbonyl species. The promotional effect of oxidized ruthenium and the role of oxygenated surface complexes in CO methanation are discussed inmore » light of the present results.« less
Elsevier eBooks, 1989
Partially-reduced ruthenium dioxide on titania is an active and selective catalyst for methane fo... more Partially-reduced ruthenium dioxide on titania is an active and selective catalyst for methane formation from carbon dioxide, already at temperatures below 100 C. Results from catalytic screening together with characterization by electron microscopy indicate that the TiO 2 support (Degussa P25 in particular) plays a major role in stabilizing metallic ruthenium in highly-dispersed form (d 10-30 A), provided care is taken in the RuO 2 deposition step. Chemisorption of H 2 and CO 2 has revealed a strong g coadsorption synergy together with extensive hydrogen spillover. Diffuse Reflectance Infrared Fourier Transform (DRIFT) Spectroscopy in situ has provided confirmatory evidence of the latter, and shown that CO, believed to arise from the reverse water-gas shift reaction accumulates on the metal causing catalyst deactivation. Heating above 100 facilitates the Boudouard disproportionation reaction and the activity is regenerated. Implications for the mechanism of CO 2 hydrogenation are briefly discussed.
CHIMIA
With the solid oxide-fuel cell, a technology exploiting ionic conductivity in electroceramic mate... more With the solid oxide-fuel cell, a technology exploiting ionic conductivity in electroceramic materials, small-scale co-generation plants for combined production of heat and electricity can achieve clean high-efficiency operation. However, with thermal activation of the cell chemistry, extremely high operating temperatures, about 1000°, are required, conditions incompatible with long term reliability using conventional structural materials. Lower-temperature operation depends decisively on the application of electrocatalysis at interfaces to the ceramic electrolyte.
Studies in Surface Science and Catalysis, 1993
ABSTRACT
Proceedings, annual meeting, Electron Microscopy Society of America, 1990
The Ru-RuOx/TiO2 catalyst has been shown to be able to produce methane from hydrogen and carbon d... more The Ru-RuOx/TiO2 catalyst has been shown to be able to produce methane from hydrogen and carbon dioxide at room temperature and atmospheric pressure at reasonably high rates (TOF: 10-6 at 25C and 10-4 at 90C). The best results were obtained using the P25 support (Degussa 80% anatase and 20% rutile) in the 55-60 m2/g surface area range. The optimal loading for the metal is 3.8% Ru metal.We found that in the most active catalysts, the metal (>90%) is selectively loaded on the rutile crystallites. This distribution shows up clearly in a 500C reduced sample (fig.l) in which the size of the metal particles has increased.