Polycrystalline SnO2 fine powder consisting of nano-particles （SnO2-NP）, SnO2 nano-sheets （SnO2-NS）, and SnO2 containing both nano-rods and nano-particles （SnO2-NR＋NP） were prepared and used for CO oxidation. S...Polycrystalline SnO2 fine powder consisting of nano-particles （SnO2-NP）, SnO2 nano-sheets （SnO2-NS）, and SnO2 containing both nano-rods and nano-particles （SnO2-NR＋NP） were prepared and used for CO oxidation. SnO2-NS possesses a mesoporous structure and has a higher surface area, larger pore volume, and more active species than SnO2-NP, and shows improved activity. In contrast, although SnO2-NR＋NP has only a slightly higher surface area and pore volume, and slightly more active surface oxygen species than SnO2-NP, it has more exposed active （110） facets, which is the reason for its improved oxidation activity. Water vapor has only a reversible and weak influence on SnO2-NS, therefore it is a potential catalyst for emission control processes.展开更多
This paper reports that the nano-sheet carbon films （NSCFs） were fabricated on Si wafer chips with hydrogen- methane gas mixture by means of quartz-tube-type microwave plasma chemical vapour deposition （MWPCVD）. I...This paper reports that the nano-sheet carbon films （NSCFs） were fabricated on Si wafer chips with hydrogen- methane gas mixture by means of quartz-tube-type microwave plasma chemical vapour deposition （MWPCVD）. In order to further improve the field emission （FE） characteristics, a 5-nm Au film was prepared on the samples by using electron beam evaporation. The FE properties were obviously improved due to depositing Au thin film on NSCFs. The FE current density at a macroscopic electric field, E, of 9 V/μm was increased from 12.4 mA/cm2 to 27.2 mA/cm2 and the threshold field was decreased from 2.6 V/μm to 2.0 V/μm for Au-coated carbon films. A modified F-N model considering statistic effects of FE tip structures in the low E region and a space-chavge-limited-current effect in the high E region were applied successfully to explain the FE data of the Au-coated NSCF.展开更多
Nano-sheet carbon films are prepared on Si wafers by means of quartz-tube microwave plasma chemical vapour deposition （MPCVD） in a gas mixture of hydrogen and methane. The structure of the fabricated films is invest...Nano-sheet carbon films are prepared on Si wafers by means of quartz-tube microwave plasma chemical vapour deposition （MPCVD） in a gas mixture of hydrogen and methane. The structure of the fabricated films is investigated by using field emission scanning electron microscope （FESEM） and Raman spectroscopy. These nano^carbon films are possessed of good field emission （FE） characteristics with a low threshold field of 2.6 V/μm and a high current density of 12.6 mA/cm^2 at an electric field of 9 V/μm. As the FE currents tend to be saturated in a high E region, no simple Fowler-Nordheim （F-N） model is applicable. A modified F N model considering statistic effects of FE tip structures and a space-charge-limited-current （SCLC） effect is applied successfully to explaining the FE data observed at low and high electric fields, respectively.展开更多
In response to thermal runaway(TR)of electric vehicles,recent attention has been focused on mitigation strategies such as efficient heat dredging in battery thermal management.Thermal management with particular focus ...In response to thermal runaway(TR)of electric vehicles,recent attention has been focused on mitigation strategies such as efficient heat dredging in battery thermal management.Thermal management with particular focus on battery cooling has been becoming increasingly significant.TR usually happened when an electric vehicle is unpowered and charged.In this state,traditional active battery cooling schemes are disabled,which can easily lead to dangerous incidents due to loss of cooling ability,and advanced passive cooling strategies are therefore gaining importance.Herein,we developed an enhanced thermal radiation material,consisting of~1μm thick multilayered nano-sheet graphene film coated upon the heat dissipation surface,thereby enhancing thermal radiation in the nanoscale.The surface was characterized on the nanoscale,and tested in a battery-cooling scenario.We found that the graphene-based coating's spectral emissivity is between 91% and 95% in the mid-infrared region,and thermal experiments consequently illustrated that graphene-based radiative cooling yielded up to15.1% temperature reduction when compared to the uncoated analogue.Using the novel graphene surface to augment a heat pipe,the temperature reduction can be further enlarged to 25.6%.The new material may contribute to transportation safety,global warming mitigation and carbon neutralization.展开更多
We developed a new one step approach to synthesize g-C3N4 nano-sheets by direct thermal pyrolysis process of urea in NH3 atmosphere. For the first time, the influence of the preparation gas atmosphere on the compositi...We developed a new one step approach to synthesize g-C3N4 nano-sheets by direct thermal pyrolysis process of urea in NH3 atmosphere. For the first time, the influence of the preparation gas atmosphere on the composition, crystalline and polymerization degree, and the activity of the g-C3N4 synthesized from thermal condensation of urea was investigated. Impressively, the g-C3N4 nano-sheets obtained under NH3 gas atmosphere exhibited much superi- or photo-catalytic activities to the prepared g-C3N4 in air or N2, and the rate of the g-C3N4-NH3 was about 5 times higher than that on g-C3N4-N2 sample. The detailed characterization analysis revealed that NH3 thermal pyrolysis atmosphere contributed to the polymerization degree and the formation of the layer with a more regular structure due to the efficiently extending of the conjugated π-conjugative system, which was favorable to the transfer of the photo-induced charge carriers. Furthermore, we studied in depth the structure-performance relationship in the sys- tem, and it was found that the synergistic effect of the larger surface area, the adjusted band energy structure and the well crystallization may be conductive to the higher separation of the electron-hole pair, thus leading to the won- derful performance for the g-C3N4-NH3. Notably, the method has the merits of low cost, scalable production and environmental friendliness.展开更多
A novel polyoxovanadate-based MOFs microsphere,[Ni(phen)V2O7]·H2O(phen=1,10-phenanthroline),constructed from 3-D discrete nano-sheets has been prepared and characterized by XRD,FT-IR,SEM and TEM.Electrochemical p...A novel polyoxovanadate-based MOFs microsphere,[Ni(phen)V2O7]·H2O(phen=1,10-phenanthroline),constructed from 3-D discrete nano-sheets has been prepared and characterized by XRD,FT-IR,SEM and TEM.Electrochemical properties as supercapacitor of the as-prepared sample,such as CV,EIS,GCD and the cycle life test have also been studied.The as-prepared MOF(V,Ni)showed a high specific capacitance of 178.09 F×g^(-1) at 1 A×g^(-1) as well as good cycling stability and coulombic efficiency.This work proved that the novel MOFs based on polyoxovanadate hybrid material may serve as a promising electrode material for high-performance supercapacitor.展开更多
Here,we report a novel visible-light-driven I^(-)doped Bi_(2)O_(2)CO_(3)nano-sheet photocatalyst synthesized via a facile ion exchange route at room temperature.This obtained Bi_(2)O_(2)CO_(3)nano-sheet with I^(-)dopi...Here,we report a novel visible-light-driven I^(-)doped Bi_(2)O_(2)CO_(3)nano-sheet photocatalyst synthesized via a facile ion exchange route at room temperature.This obtained Bi_(2)O_(2)CO_(3)nano-sheet with I^(-)doping shows several ad-vantages.The specific surface area of I_(0.875)-Bi_(2)O_(2)CO_(3)is 2.16 times higher than that of Bi_(2)O_(2)CO_(3),providing more catalytic sites for the degradation reactions.Moreover,a 3.2 times photocurrent enhancement is observed in I_(0.875)-Bi_(2)O_(2)CO_(3)compared with Bi_(2)O_(2)CO_(3),producing more photogenerated electron-hole pairs for degradation.The synergistic effect between texture property and photoelectric effect boosts the removal of organic pollutants.Under visible light illumination,I_(0.875)-Bi_(2)O_(2)CO_(3)displays superior photocatalytic performance for the degradation of methyl orange(MO)and phenol.Notably,a phenol degradation rate,88%,is achieved by I_(0.875)-Bi_(2)O_(2)CO_(3)with illuminating for 60 min,which is about 29 times higher than that of pristine Bi_(2)O_(2)CO_(3).This finding may provide an opportunity to develop a promising I^(-)doped catalyst for organic pollutants removal.展开更多
MXenes,a newly emerging class of layered two dimensional(2D)materials,are promising solid lubricants due to their 2D structure consisting of weakly-bonded layers with a low shear strength and ability to form beneficia...MXenes,a newly emerging class of layered two dimensional(2D)materials,are promising solid lubricants due to their 2D structure consisting of weakly-bonded layers with a low shear strength and ability to form beneficial tribo-layers.This work aims at evaluating for the first time MXenes lubrication performance and tribofilm formation ability on different metallic substrates(mirror-lapped Fe and Cu discs).After depositing MXenes via ethanol(1 wt%)on the substrates,pronounced differences in the resulting substrate-dependent frictional evolution are observed.While MXenes are capable to reduce friction for both substrates after the full evaporation of ethanol,MXenes lubricating effect on Cu is long-lasting,with a 35-fold increased lifetime compared to Fe.Raman spectra acquired in the wear-tracks of the substrates and counter-bodies reveal notable differences in the friction-induced chemical changes depending on the substrate material.In case of Fe,the progressive failure of MXenes lubrication generates different Fe oxides on both the substrate and the ball,resulting in continuously increasing friction and a poor lubrication effect.For Cu,sliding induces the formation of a Ti_(3)C_(2)-based tribofilm on both rubbing surfaces,enabling a long-lasting lubricating effect.This work boosts further experimental and theoretical work on MXenes involved tribo-chemical processes.展开更多
基金supported by the National Natural Science Foundation of China (21263015)the Education Department of Jiangxi Province (KJLD14005)the Natural Science Foundation of Jiangxi Province(20151BBE50006,20122BAB203009)~~
文摘Polycrystalline SnO2 fine powder consisting of nano-particles （SnO2-NP）, SnO2 nano-sheets （SnO2-NS）, and SnO2 containing both nano-rods and nano-particles （SnO2-NR＋NP） were prepared and used for CO oxidation. SnO2-NS possesses a mesoporous structure and has a higher surface area, larger pore volume, and more active species than SnO2-NP, and shows improved activity. In contrast, although SnO2-NR＋NP has only a slightly higher surface area and pore volume, and slightly more active surface oxygen species than SnO2-NP, it has more exposed active （110） facets, which is the reason for its improved oxidation activity. Water vapor has only a reversible and weak influence on SnO2-NS, therefore it is a potential catalyst for emission control processes.
文摘This paper reports that the nano-sheet carbon films （NSCFs） were fabricated on Si wafer chips with hydrogen- methane gas mixture by means of quartz-tube-type microwave plasma chemical vapour deposition （MWPCVD）. In order to further improve the field emission （FE） characteristics, a 5-nm Au film was prepared on the samples by using electron beam evaporation. The FE properties were obviously improved due to depositing Au thin film on NSCFs. The FE current density at a macroscopic electric field, E, of 9 V/μm was increased from 12.4 mA/cm2 to 27.2 mA/cm2 and the threshold field was decreased from 2.6 V/μm to 2.0 V/μm for Au-coated carbon films. A modified F-N model considering statistic effects of FE tip structures in the low E region and a space-chavge-limited-current effect in the high E region were applied successfully to explain the FE data of the Au-coated NSCF.
文摘Nano-sheet carbon films are prepared on Si wafers by means of quartz-tube microwave plasma chemical vapour deposition （MPCVD） in a gas mixture of hydrogen and methane. The structure of the fabricated films is investigated by using field emission scanning electron microscope （FESEM） and Raman spectroscopy. These nano^carbon films are possessed of good field emission （FE） characteristics with a low threshold field of 2.6 V/μm and a high current density of 12.6 mA/cm^2 at an electric field of 9 V/μm. As the FE currents tend to be saturated in a high E region, no simple Fowler-Nordheim （F-N） model is applicable. A modified F N model considering statistic effects of FE tip structures and a space-charge-limited-current （SCLC） effect is applied successfully to explaining the FE data observed at low and high electric fields, respectively.
基金supported by the National Natural Science Foundation of China(no.52106114)Beijing Natural Science Foundation(no.3234061)Hong Kong Scholars Program(no.XJ2022027)。
文摘In response to thermal runaway(TR)of electric vehicles,recent attention has been focused on mitigation strategies such as efficient heat dredging in battery thermal management.Thermal management with particular focus on battery cooling has been becoming increasingly significant.TR usually happened when an electric vehicle is unpowered and charged.In this state,traditional active battery cooling schemes are disabled,which can easily lead to dangerous incidents due to loss of cooling ability,and advanced passive cooling strategies are therefore gaining importance.Herein,we developed an enhanced thermal radiation material,consisting of~1μm thick multilayered nano-sheet graphene film coated upon the heat dissipation surface,thereby enhancing thermal radiation in the nanoscale.The surface was characterized on the nanoscale,and tested in a battery-cooling scenario.We found that the graphene-based coating's spectral emissivity is between 91% and 95% in the mid-infrared region,and thermal experiments consequently illustrated that graphene-based radiative cooling yielded up to15.1% temperature reduction when compared to the uncoated analogue.Using the novel graphene surface to augment a heat pipe,the temperature reduction can be further enlarged to 25.6%.The new material may contribute to transportation safety,global warming mitigation and carbon neutralization.
文摘We developed a new one step approach to synthesize g-C3N4 nano-sheets by direct thermal pyrolysis process of urea in NH3 atmosphere. For the first time, the influence of the preparation gas atmosphere on the composition, crystalline and polymerization degree, and the activity of the g-C3N4 synthesized from thermal condensation of urea was investigated. Impressively, the g-C3N4 nano-sheets obtained under NH3 gas atmosphere exhibited much superi- or photo-catalytic activities to the prepared g-C3N4 in air or N2, and the rate of the g-C3N4-NH3 was about 5 times higher than that on g-C3N4-N2 sample. The detailed characterization analysis revealed that NH3 thermal pyrolysis atmosphere contributed to the polymerization degree and the formation of the layer with a more regular structure due to the efficiently extending of the conjugated π-conjugative system, which was favorable to the transfer of the photo-induced charge carriers. Furthermore, we studied in depth the structure-performance relationship in the sys- tem, and it was found that the synergistic effect of the larger surface area, the adjusted band energy structure and the well crystallization may be conductive to the higher separation of the electron-hole pair, thus leading to the won- derful performance for the g-C3N4-NH3. Notably, the method has the merits of low cost, scalable production and environmental friendliness.
基金supported by the Natural Science Foundation of Fujian Province(No.2020J01803)Fujian Provincial Key Laboratory of Featured Materials in Biochemical Industry(FJKL_FBCM202004)the Fujian Provincial Key Laboratory of Ecotoxicological Effects and Control of New Pollutants(PY19001)。
文摘A novel polyoxovanadate-based MOFs microsphere,[Ni(phen)V2O7]·H2O(phen=1,10-phenanthroline),constructed from 3-D discrete nano-sheets has been prepared and characterized by XRD,FT-IR,SEM and TEM.Electrochemical properties as supercapacitor of the as-prepared sample,such as CV,EIS,GCD and the cycle life test have also been studied.The as-prepared MOF(V,Ni)showed a high specific capacitance of 178.09 F×g^(-1) at 1 A×g^(-1) as well as good cycling stability and coulombic efficiency.This work proved that the novel MOFs based on polyoxovanadate hybrid material may serve as a promising electrode material for high-performance supercapacitor.
基金the National Natural Science Foundation of China(No.22272034)Environment and Energy Green Catalysis Innovation Team of Colleges and Universities of Guangdong Province(2022KCXTD019)+2 种基金Maoming City Science and Technology Project(2023SZX034)2024 Provincial Student Innovation Training Project(24B096)Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(2019).
文摘Here,we report a novel visible-light-driven I^(-)doped Bi_(2)O_(2)CO_(3)nano-sheet photocatalyst synthesized via a facile ion exchange route at room temperature.This obtained Bi_(2)O_(2)CO_(3)nano-sheet with I^(-)doping shows several ad-vantages.The specific surface area of I_(0.875)-Bi_(2)O_(2)CO_(3)is 2.16 times higher than that of Bi_(2)O_(2)CO_(3),providing more catalytic sites for the degradation reactions.Moreover,a 3.2 times photocurrent enhancement is observed in I_(0.875)-Bi_(2)O_(2)CO_(3)compared with Bi_(2)O_(2)CO_(3),producing more photogenerated electron-hole pairs for degradation.The synergistic effect between texture property and photoelectric effect boosts the removal of organic pollutants.Under visible light illumination,I_(0.875)-Bi_(2)O_(2)CO_(3)displays superior photocatalytic performance for the degradation of methyl orange(MO)and phenol.Notably,a phenol degradation rate,88%,is achieved by I_(0.875)-Bi_(2)O_(2)CO_(3)with illuminating for 60 min,which is about 29 times higher than that of pristine Bi_(2)O_(2)CO_(3).This finding may provide an opportunity to develop a promising I^(-)doped catalyst for organic pollutants removal.
基金A.Rosenkranz gratefully acknowledges the financial support given by ANID(Chile)in the framework of the Fondecyt projects 1220331 and EQM190057.In addition,A.Rosenkranz acknowledges the support from the University of Chile and VID in the framework of U-Moderniza UM-04/19.
文摘MXenes,a newly emerging class of layered two dimensional(2D)materials,are promising solid lubricants due to their 2D structure consisting of weakly-bonded layers with a low shear strength and ability to form beneficial tribo-layers.This work aims at evaluating for the first time MXenes lubrication performance and tribofilm formation ability on different metallic substrates(mirror-lapped Fe and Cu discs).After depositing MXenes via ethanol(1 wt%)on the substrates,pronounced differences in the resulting substrate-dependent frictional evolution are observed.While MXenes are capable to reduce friction for both substrates after the full evaporation of ethanol,MXenes lubricating effect on Cu is long-lasting,with a 35-fold increased lifetime compared to Fe.Raman spectra acquired in the wear-tracks of the substrates and counter-bodies reveal notable differences in the friction-induced chemical changes depending on the substrate material.In case of Fe,the progressive failure of MXenes lubrication generates different Fe oxides on both the substrate and the ball,resulting in continuously increasing friction and a poor lubrication effect.For Cu,sliding induces the formation of a Ti_(3)C_(2)-based tribofilm on both rubbing surfaces,enabling a long-lasting lubricating effect.This work boosts further experimental and theoretical work on MXenes involved tribo-chemical processes.
基金Natural Science Foundation of Fujian Province China(No.A0320001),the Ministry of Science and Technology of China(No.2003BA323C),andthe State Key Laboratory of Structural Chemistry of China(No.050005).
