Nitric oxide(NO),which generally originates from vehicle exhaust and industrial flue gases,is one of the most serious air pollutants.In this case,the electrochemical NO reduction reaction(NORR)not only removes the atm...Nitric oxide(NO),which generally originates from vehicle exhaust and industrial flue gases,is one of the most serious air pollutants.In this case,the electrochemical NO reduction reaction(NORR)not only removes the atmospheric pollutant NO but also produces valuable ammonia(NH_(3)).Hence,through the synthesis and modification of Fe_(3)C nanocrystal cata-lysts,the as-obtained optimal sample of Fe_(3)C/C-900 was adopted as the NORR catalyst at ambient conditions.As a result,the Fe_(3)C/C-900 catalyst showed an NH_(3)Faraday efficiency of 76.5%and an NH_(3)yield rate of 177.5μmol·h^(-1)·cm^(-2)at the working potentials of-0.8 and-1.2 V versus reversible hydrogen electrode(vs.RHE),respectively.And it delivered a stable NORR activity during the electrolysis.Moreover,we attribute the high NORR properties of Fe_(3)C/C-900 to two aspects:one is the enhanced intrinsic activity of Fe_(3)C nanocrystals,including the lowering of the energy barrier of rate-limiting step(*NOH→*N)and the inhibition of hydrogen evolution;on the other hand,the favorable dispersion of active components,the effective adsorption of gaseous NO,and the release of liquid NH_(3)products facilitated by the porous carbon substrate.展开更多
The structural evolution and optical characterization of hydrogenated silicon(Si:H) thin films obtained by conventional radio frequency(RF) plasma enhanced chemical vapor deposition(PECVD) through decomposition of sil...The structural evolution and optical characterization of hydrogenated silicon(Si:H) thin films obtained by conventional radio frequency(RF) plasma enhanced chemical vapor deposition(PECVD) through decomposition of silane diluted with argon were studied by X-ray diffractometry(XRD),Fourier transform infrared(FTIR) spectroscopy,Raman spectroscopy,transmission electron microscopy(TEM),and ultraviolet and visible(UV-vis) spectroscopy,respectively.The influence of argon dilution on the optical properties of the thin films was also studied.It is found that argon as dilution gas plays a significant role in the growth of nano-crystal grains and amorphous network in Si:H thin films.The structural evolution of the thin films with different argon dilution ratios is observed and it is suggested that argon plasma leads to the nanocrystallization in the thin films during the deposition process.The nanocrystallization initiating at a relatively low dilution ratio is also observed.With the increase of argon portion in the mixed precursor gases,nano-crystal grains in the thin films evolve regularly.The structural evolution is explained by a proposed model based on the energy exchange between the argon plasma constituted with Ar* and Ar+ radicals and the growth regions of the thin films.It is observed that both the absorption of UV-vis light and the optical gap decrease with the increase of dilution ratio.展开更多
As a popular anode material for lithium-ion batteries,anatase TiO2 nanoparticles with exposed{001}facets usually exhibit exceptional lithium storage performance owing to more accessible sites and fast migration of lit...As a popular anode material for lithium-ion batteries,anatase TiO2 nanoparticles with exposed{001}facets usually exhibit exceptional lithium storage performance owing to more accessible sites and fast migration of lithium ions along the good crystalline channels.However,there are few researches on the lithium storage capability of TiO2 nanocrystals with other high-energy facets owing to lack of effective synthesis method for controlling crystal facets.Herein,anatase TiO2 nanocrystals with exposed{010}-and[111]-facets are successfully prepared by using the delaminated tetratitanate nanoribbons as precursors.The electrochemical properties of these TiO2 nanocrystals with high-energy surfaces and the comparison with commercial TiO2 nanoparticles(P25)are studied.It is found that the cycle and rate performance of TiO2 nanocrystals is highly improved by reducing the particle size of nanocrystals.Moreover,TiO2 nanocrystals with exposed{010}-and[111]-facets exhibit better lithium storage capacities in comparison with P25 without a specific facet though P25 has smaller particle size than these TiO2 nanocrystals,indicating that the exposed facets of TiO2 nanocrystals have an important impact on their lithium storage capacity.Therefore,the synthesis design of high-performance TiO2 materials applied in the next-generation secondary batteries should both consider the particle size and the exposed facets of nanocrystals.展开更多
The effect of additive RCOONa on the formation of MnZn ferrite homogeneous coprecipitation precursor was studied in this paper. The action of additive in the MnZn ferrite hydrothermal crystallization process was inves...The effect of additive RCOONa on the formation of MnZn ferrite homogeneous coprecipitation precursor was studied in this paper. The action of additive in the MnZn ferrite hydrothermal crystallization process was investigated according to crystal field theory and crystal growth unit theory. And the growth unit formation process was presented and its structure was illustrated. The results show that the precursor of MnZn ferrite is a colloidal mixture composed of Zn(OH) 2, Fe(OH) 2, Mn(OH) 2, MnO(OH) , MnO 2· x H 2O and so on, and dissolves in solution in the form of hydroxyl coordination tetrahedron and octahedron such as Zn(OH) 2- 4, Fe(OH) 2- 4, Fe(OH) 4- 6,Fe(OH) - 4, Fe(OH) 3- 6,Mn(OH) 2- 4,Mn(OH) 3- 6 etc., and the growth unit is formed by combination of the coordination polyhedra subsequently in the hydrothermal precess. The additive is beneficial to the formation of homogeneous precursor and has dispersive effect on the aggregation of the crystal growth unit by forming associate with hydrogen bond, which is beneficial to the synthesis of the pure product with a tiny size and a narrow size distribution.展开更多
In recent years, the increasing demand of various fields of radiation detection materials has led to intensive researches in scintillation materials 1-2]. The scintillators can absorb high-energy X-ray photons and the...In recent years, the increasing demand of various fields of radiation detection materials has led to intensive researches in scintillation materials 1-2]. The scintillators can absorb high-energy X-ray photons and then convert them into low-energy visible photons, which are widely applied in radiation monitoring, security detection, X-ray astronomy and medical radiology 3"l].展开更多
Monodispersed manganese ferrite （MnFe2O4） nanocrystals could be successfully synthesized in large quantities via a facile synthetic technique based on the pyrolysis of organometallic compound precursor, in which oct...Monodispersed manganese ferrite （MnFe2O4） nanocrystals could be successfully synthesized in large quantities via a facile synthetic technique based on the pyrolysis of organometallic compound precursor, in which octadecene was used as solvent, and oleic acid and oleylamine were used as capping ligands. MnFe204 nanocrystals were obtained with size in a tunable range of 4- 15 nm and their morphologies could be tuned from spherical to triangle-shaped by varying the surfactants. The phase structure, morphology, and size of the products were characterized in detail by X-ray diffraction （XRD） and transmission electron microscopy （TEM）. Magnetic properties of MnFe2O4 nanocrystals with different morphologies were measured using a superconducting quantum interference device （SQUID）. Both monodisperse MnFe204 nanocrystals with spherical and triangle-shapes are superparamagnetic at room temperature while ferromagnetic at 2 K. The pyrolysis method may provide an effective route to synthesize other spinel ferrites or metal oxides nanocrystals.展开更多
基金supported by the Guangxi Natural Science Fund for Distinguished Young Scholars(2024GXNSFFA010008)Shenzhen Science and Technology Program(JCYJ20230807112503008).
文摘Nitric oxide(NO),which generally originates from vehicle exhaust and industrial flue gases,is one of the most serious air pollutants.In this case,the electrochemical NO reduction reaction(NORR)not only removes the atmospheric pollutant NO but also produces valuable ammonia(NH_(3)).Hence,through the synthesis and modification of Fe_(3)C nanocrystal cata-lysts,the as-obtained optimal sample of Fe_(3)C/C-900 was adopted as the NORR catalyst at ambient conditions.As a result,the Fe_(3)C/C-900 catalyst showed an NH_(3)Faraday efficiency of 76.5%and an NH_(3)yield rate of 177.5μmol·h^(-1)·cm^(-2)at the working potentials of-0.8 and-1.2 V versus reversible hydrogen electrode(vs.RHE),respectively.And it delivered a stable NORR activity during the electrolysis.Moreover,we attribute the high NORR properties of Fe_(3)C/C-900 to two aspects:one is the enhanced intrinsic activity of Fe_(3)C nanocrystals,including the lowering of the energy barrier of rate-limiting step(*NOH→*N)and the inhibition of hydrogen evolution;on the other hand,the favorable dispersion of active components,the effective adsorption of gaseous NO,and the release of liquid NH_(3)products facilitated by the porous carbon substrate.
基金Project(60425101) supported by the National Outstanding Young Scientists Foundation of ChinaProject(06DZ0241) supported by the Science Foundation of General Armament Department of China
文摘The structural evolution and optical characterization of hydrogenated silicon(Si:H) thin films obtained by conventional radio frequency(RF) plasma enhanced chemical vapor deposition(PECVD) through decomposition of silane diluted with argon were studied by X-ray diffractometry(XRD),Fourier transform infrared(FTIR) spectroscopy,Raman spectroscopy,transmission electron microscopy(TEM),and ultraviolet and visible(UV-vis) spectroscopy,respectively.The influence of argon dilution on the optical properties of the thin films was also studied.It is found that argon as dilution gas plays a significant role in the growth of nano-crystal grains and amorphous network in Si:H thin films.The structural evolution of the thin films with different argon dilution ratios is observed and it is suggested that argon plasma leads to the nanocrystallization in the thin films during the deposition process.The nanocrystallization initiating at a relatively low dilution ratio is also observed.With the increase of argon portion in the mixed precursor gases,nano-crystal grains in the thin films evolve regularly.The structural evolution is explained by a proposed model based on the energy exchange between the argon plasma constituted with Ar* and Ar+ radicals and the growth regions of the thin films.It is observed that both the absorption of UV-vis light and the optical gap decrease with the increase of dilution ratio.
基金Projects(21573023,51572031)supported by the National Natural Science Foundation of ChinaProject supported by the Grants-in-Acid for Doctor Research Funds+1 种基金Project supported by “1331 Project” for Innovation Team Construction Plan Funds of Jinzhong University,ChinaProject supported by “1331 Project” for 2018 Key Innovation Team Construction Plan Funds of Shanxi Province,China
文摘As a popular anode material for lithium-ion batteries,anatase TiO2 nanoparticles with exposed{001}facets usually exhibit exceptional lithium storage performance owing to more accessible sites and fast migration of lithium ions along the good crystalline channels.However,there are few researches on the lithium storage capability of TiO2 nanocrystals with other high-energy facets owing to lack of effective synthesis method for controlling crystal facets.Herein,anatase TiO2 nanocrystals with exposed{010}-and[111]-facets are successfully prepared by using the delaminated tetratitanate nanoribbons as precursors.The electrochemical properties of these TiO2 nanocrystals with high-energy surfaces and the comparison with commercial TiO2 nanoparticles(P25)are studied.It is found that the cycle and rate performance of TiO2 nanocrystals is highly improved by reducing the particle size of nanocrystals.Moreover,TiO2 nanocrystals with exposed{010}-and[111]-facets exhibit better lithium storage capacities in comparison with P25 without a specific facet though P25 has smaller particle size than these TiO2 nanocrystals,indicating that the exposed facets of TiO2 nanocrystals have an important impact on their lithium storage capacity.Therefore,the synthesis design of high-performance TiO2 materials applied in the next-generation secondary batteries should both consider the particle size and the exposed facets of nanocrystals.
文摘The effect of additive RCOONa on the formation of MnZn ferrite homogeneous coprecipitation precursor was studied in this paper. The action of additive in the MnZn ferrite hydrothermal crystallization process was investigated according to crystal field theory and crystal growth unit theory. And the growth unit formation process was presented and its structure was illustrated. The results show that the precursor of MnZn ferrite is a colloidal mixture composed of Zn(OH) 2, Fe(OH) 2, Mn(OH) 2, MnO(OH) , MnO 2· x H 2O and so on, and dissolves in solution in the form of hydroxyl coordination tetrahedron and octahedron such as Zn(OH) 2- 4, Fe(OH) 2- 4, Fe(OH) 4- 6,Fe(OH) - 4, Fe(OH) 3- 6,Mn(OH) 2- 4,Mn(OH) 3- 6 etc., and the growth unit is formed by combination of the coordination polyhedra subsequently in the hydrothermal precess. The additive is beneficial to the formation of homogeneous precursor and has dispersive effect on the aggregation of the crystal growth unit by forming associate with hydrogen bond, which is beneficial to the synthesis of the pure product with a tiny size and a narrow size distribution.
文摘In recent years, the increasing demand of various fields of radiation detection materials has led to intensive researches in scintillation materials 1-2]. The scintillators can absorb high-energy X-ray photons and then convert them into low-energy visible photons, which are widely applied in radiation monitoring, security detection, X-ray astronomy and medical radiology 3"l].
基金Project(2010QZZD008) supported by the Prospect Key Projects of Fundamental Research Funds for the Central UniversitiesProject(2007FJ3008) supported by the Hunan Provincial Key Science and Technology Program of China
文摘Monodispersed manganese ferrite （MnFe2O4） nanocrystals could be successfully synthesized in large quantities via a facile synthetic technique based on the pyrolysis of organometallic compound precursor, in which octadecene was used as solvent, and oleic acid and oleylamine were used as capping ligands. MnFe204 nanocrystals were obtained with size in a tunable range of 4- 15 nm and their morphologies could be tuned from spherical to triangle-shaped by varying the surfactants. The phase structure, morphology, and size of the products were characterized in detail by X-ray diffraction （XRD） and transmission electron microscopy （TEM）. Magnetic properties of MnFe2O4 nanocrystals with different morphologies were measured using a superconducting quantum interference device （SQUID）. Both monodisperse MnFe204 nanocrystals with spherical and triangle-shapes are superparamagnetic at room temperature while ferromagnetic at 2 K. The pyrolysis method may provide an effective route to synthesize other spinel ferrites or metal oxides nanocrystals.
