The Experts below are selected from a list of 165 Experts worldwide ranked by ideXlab platform
W R Flavell - One of the best experts on this subject based on the ideXlab platform.
-
photocatalytic hydrogen production by biomimetic indium sulfide using mimosa pudica leaves as template
International Journal of Hydrogen Energy, 2019Co-Authors: Omar A Carrascojaim, Ruben Ahumadalazo, Pip C J Clark, Christian Gomezsolis, Simon M Fairclough, Sarah J Haigh, Marina A Leontiadou, Karsten Handrup, Leticia M Torresmartinez, W R FlavellAbstract:Abstract Biomimetic Sulfur-deficient indium sulfide (In 2.77 S 4 ) was synthesized by a template-assisted hydrothermal method using leaves of Mimosa pudica as a template for the first time. The effect of this template in modifying the morphology of the semiconductor particles was determined by physicochemical characterization, revealing an increase in surface area, decrease in microsphere size and pore size and an increase in pore volume density in samples synthesized with the template. X-ray photoelectron spectroscopy (XPS) analysis showed the presence of organic Sulfur (S O/S C/S H) and Sulfur Oxide species ( SO 2 , SO 3 2− , SO 4 2− ) at the surface of the indium sulfide in samples synthesized with the template. Biomimetic indium sulfide also showed significant amounts of Fe introduced as a contaminant present on the Mimosa pudica leaves. The presence of these Sulfur and iron species favors the photocatalytic activity for hydrogen production by their acting as a sacrificial reagent and promoting water oxidation on the surface of the templated particles, respectively. The photocatalytic hydrogen production rates over optimally-prepared biomimetic indium sulfide and indium sulfide synthesized without the organic template were 73 and 22 μmol g −1 , respectively, indicating an improvement by a factor of three in the templated sample.
Omar A Carrascojaim - One of the best experts on this subject based on the ideXlab platform.
-
photocatalytic hydrogen production by biomimetic indium sulfide using mimosa pudica leaves as template
International Journal of Hydrogen Energy, 2019Co-Authors: Omar A Carrascojaim, Ruben Ahumadalazo, Pip C J Clark, Christian Gomezsolis, Simon M Fairclough, Sarah J Haigh, Marina A Leontiadou, Karsten Handrup, Leticia M Torresmartinez, W R FlavellAbstract:Abstract Biomimetic Sulfur-deficient indium sulfide (In 2.77 S 4 ) was synthesized by a template-assisted hydrothermal method using leaves of Mimosa pudica as a template for the first time. The effect of this template in modifying the morphology of the semiconductor particles was determined by physicochemical characterization, revealing an increase in surface area, decrease in microsphere size and pore size and an increase in pore volume density in samples synthesized with the template. X-ray photoelectron spectroscopy (XPS) analysis showed the presence of organic Sulfur (S O/S C/S H) and Sulfur Oxide species ( SO 2 , SO 3 2− , SO 4 2− ) at the surface of the indium sulfide in samples synthesized with the template. Biomimetic indium sulfide also showed significant amounts of Fe introduced as a contaminant present on the Mimosa pudica leaves. The presence of these Sulfur and iron species favors the photocatalytic activity for hydrogen production by their acting as a sacrificial reagent and promoting water oxidation on the surface of the templated particles, respectively. The photocatalytic hydrogen production rates over optimally-prepared biomimetic indium sulfide and indium sulfide synthesized without the organic template were 73 and 22 μmol g −1 , respectively, indicating an improvement by a factor of three in the templated sample.
Roman Anthony - One of the best experts on this subject based on the ideXlab platform.
-
On Venus' cloud top chemistry, convective activity and topography: A perspective from HST
'Elsevier BV', 2020Co-Authors: Jessup Kandis-lea, Marcq Emmanuel, Bertaux Jean-loup, Mills, Franklin P., Limaye Sanjay, Roman AnthonyAbstract:International audienceHubble Space Telescope Imaging Spectrograph (HST/STIS) observations were obtained on 3 dates in December 2010 and January 2011 recording the cloud top properties over Aphrodite Terra and a low elevation region downwind of Aphrodite through LSTs extending from 7 to 11 a.m. From these data we trace the cloud top Sulfur-Oxide chemistry and UV albedo sensitivity to LST, latitude and topography. Above regions co-located in LST and latitude, albedo variations observed at 245 nm parallel those observed at 365 nm-following the pattern expected from Hadley cell circulation. However, darkening of the cloud top albedo at LSTs between 9.5 and 11 h beyond that expected from simple Hadley circulation was also observed. Above the plains the albedo darkening intensified rapidly with LST and was observed at latitudes extending as high as ~30 N; however, above the mountains the darkening was either entirely absent or evident only at 0 N at an intensity 2× lower than that observed over the plains. Because the observed 245 nm albedo LST variations were inconsistent with that expected from multiple scattering of the coincidently retrieved SO2 gas abundance, we conclude that the 245 nm albedo is diagnostic of the vertical and spatial distribution, abundance (and potentially the identity) of Venus' unidentified UV absorber—rather than SO2 gas. The LST albedo trends are best explained by the onset of subsolar convective activity that intensifies with LST expanding vertically from the boundary between the middle and upper clouds to the cloud tops and increasing the detectability of the unknown absorbing species at the cloud tops. The terrain dependence in the observed intensity implies the time at which the expansion reaches the cloud tops is later above the mountains than over the plains. Additionally, at the time of observation, the low-latitude large-scale vertical mixing rates that control the latitudinal gradients of the SO2 and unknown absorber abundances above and within the cloud top region were lower over Aphrodite Terra than the plains, to the extent that photochemical processing destroyed the spatial correlation between those absorbing species. These observations show the power of UV spectroscopy to diagnose the distinct influences of deep (Hadley-cell type) and shallow convective mixing processes on the vertical and horizontal distribution of Venus' unknown absorbing species, and the sensitivity of these processes to LST and topography, relative to the Sulfur Oxide chemistry. These results are essential for accurate climate modeling—and when compared to recent Venus missions motivate a need for additional follow-on observing campaigns that simultaneously trace key cloud top chemistry and dynamic processes including the LST dependent evolution of planetary scale gravity waves (GWs). With the inevitable aging of the Hubble Telescope, follow-on observations providing temporally coincident traces of the cloud top albedo, Sulfur-Oxide chemistry and GW features will require a new age of space-based telescopes and Venus orbiting mission with sensitivity to UV, visible and IR wavelengths
-
On Venus' cloud top chemistry, convective activity and topography: A perspective from HST
'Elsevier BV', 2020Co-Authors: Jessup, Kandis Lea, Bertaux Jean-loup, Limaye Sanjay, Marcq E., Mills Franklin, Roman AnthonyAbstract:Hubble Space Telescope Imaging Spectrograph (HST/STIS) observations were obtained on 3 dates in December 2010 and January 2011 recording the cloud top properties over Aphrodite Terra and a low elevation region downwind of Aphrodite through LSTs extending from 7 to 11 a.m. From these data we trace the cloud top SulfurOxide chemistry and UV albedo sensitivity to LST, latitude and topography. Above regions co-located in LST and latitude, albedo variations observed at 245 nm parallel those observed at 365 nm-following the pattern expected from Hadley cell circulation. However, darkening of the cloud top albedo at LSTs between 9.5 and 11 h beyond that expected from simple Hadley circulation was also observed. Above the plains the albedo darkening intensified rapidly with LST and was observed at latitudes extending as high as ~30 N; however, above the mountains the darkening was either entirely absent or evident only at 0 N at an intensity 2× lower than that observed over the plains. Because the observed 245 nm albedo LST variations were inconsistent with that expected from multiple scattering of the coincidently retrieved SO2 gas abundance, we conclude that the 245 nm albedo is diagnostic of the vertical and spatial distribution, abundance (and potentially the identity) of Venus' unidentified UV absorber—rather than SO2 gas. The LST albedo trends are best explained by the onset of subsolar convective activity that intensifies with LST expanding vertically from the boundary between the middle and upper clouds to the cloud tops and increasing the detectability of the unknown absorbing species at the cloud tops. The terrain dependence in the observed intensity implies the time at which the expansion reaches the cloud tops is later above the mountains than over the plains. Additionally, at the time of observation, the lowlatitude large-scale vertical mixing rates that control the latitudinal gradients of the SO2 and unknown absorber abundances above and within the cloud top region were lower over Aphrodite Terra than the plains, to the extent that photochemical processing destroyed the spatial correlation between those absorbing species. These observations show the power of UV spectroscopy to diagnose the distinct influences of deep (Hadley-cell type) and shallow convective mixing processes on the vertical and horizontal distribution of Venus' unknown absorbing species, and the sensitivity of these processes to LST and topography, relative to the Sulfur Oxide chemistry. These results are essential for accurate climate modeling—and when compared to recent Venus missions motivate a need for additional follow-on observing campaigns that simultaneously trace key cloud top chemistry and dynamic processes including the LST dependent evolution of planetary scale gravity waves (GWs). With the inevitable aging of the Hubble Telescope, follow-on observations providing temporally coincident traces of the cloud top albedo, Sulfur-Oxide chemistry and GW features will require a new age of space-based telescopes and Venus orbiting mission with sensitivity to UV, visible and IR wavelengths.This research was funded through the NASA Venus Climate Orbiter Participating Scientist program, NASA Grant NNX16AK82G (Jessup); NNX16AC79G (Limaye). F.P. Mills acknowledges partial support under NASA Grant NNX12AI32G and NNX16AN03G to Space Science Institute. E. Marcq acknowledges support from CNES and from the Programme National de Planétologie (PNP) of CNRS/INSU
Ruben Ahumadalazo - One of the best experts on this subject based on the ideXlab platform.
-
photocatalytic hydrogen production by biomimetic indium sulfide using mimosa pudica leaves as template
International Journal of Hydrogen Energy, 2019Co-Authors: Omar A Carrascojaim, Ruben Ahumadalazo, Pip C J Clark, Christian Gomezsolis, Simon M Fairclough, Sarah J Haigh, Marina A Leontiadou, Karsten Handrup, Leticia M Torresmartinez, W R FlavellAbstract:Abstract Biomimetic Sulfur-deficient indium sulfide (In 2.77 S 4 ) was synthesized by a template-assisted hydrothermal method using leaves of Mimosa pudica as a template for the first time. The effect of this template in modifying the morphology of the semiconductor particles was determined by physicochemical characterization, revealing an increase in surface area, decrease in microsphere size and pore size and an increase in pore volume density in samples synthesized with the template. X-ray photoelectron spectroscopy (XPS) analysis showed the presence of organic Sulfur (S O/S C/S H) and Sulfur Oxide species ( SO 2 , SO 3 2− , SO 4 2− ) at the surface of the indium sulfide in samples synthesized with the template. Biomimetic indium sulfide also showed significant amounts of Fe introduced as a contaminant present on the Mimosa pudica leaves. The presence of these Sulfur and iron species favors the photocatalytic activity for hydrogen production by their acting as a sacrificial reagent and promoting water oxidation on the surface of the templated particles, respectively. The photocatalytic hydrogen production rates over optimally-prepared biomimetic indium sulfide and indium sulfide synthesized without the organic template were 73 and 22 μmol g −1 , respectively, indicating an improvement by a factor of three in the templated sample.
Leticia M Torresmartinez - One of the best experts on this subject based on the ideXlab platform.
-
photocatalytic hydrogen production by biomimetic indium sulfide using mimosa pudica leaves as template
International Journal of Hydrogen Energy, 2019Co-Authors: Omar A Carrascojaim, Ruben Ahumadalazo, Pip C J Clark, Christian Gomezsolis, Simon M Fairclough, Sarah J Haigh, Marina A Leontiadou, Karsten Handrup, Leticia M Torresmartinez, W R FlavellAbstract:Abstract Biomimetic Sulfur-deficient indium sulfide (In 2.77 S 4 ) was synthesized by a template-assisted hydrothermal method using leaves of Mimosa pudica as a template for the first time. The effect of this template in modifying the morphology of the semiconductor particles was determined by physicochemical characterization, revealing an increase in surface area, decrease in microsphere size and pore size and an increase in pore volume density in samples synthesized with the template. X-ray photoelectron spectroscopy (XPS) analysis showed the presence of organic Sulfur (S O/S C/S H) and Sulfur Oxide species ( SO 2 , SO 3 2− , SO 4 2− ) at the surface of the indium sulfide in samples synthesized with the template. Biomimetic indium sulfide also showed significant amounts of Fe introduced as a contaminant present on the Mimosa pudica leaves. The presence of these Sulfur and iron species favors the photocatalytic activity for hydrogen production by their acting as a sacrificial reagent and promoting water oxidation on the surface of the templated particles, respectively. The photocatalytic hydrogen production rates over optimally-prepared biomimetic indium sulfide and indium sulfide synthesized without the organic template were 73 and 22 μmol g −1 , respectively, indicating an improvement by a factor of three in the templated sample.
