A graphite carbon nitride(g-C3N4)modified Bi4O5I2 composite was successfully prepared insitu via the thermal treatment of a g-C3N4/Bi OI precursor at 400°C for 3 hr.The as-prepared g-C3N4/Bi4O5I2 showed high phot...A graphite carbon nitride(g-C3N4)modified Bi4O5I2 composite was successfully prepared insitu via the thermal treatment of a g-C3N4/Bi OI precursor at 400°C for 3 hr.The as-prepared g-C3N4/Bi4O5I2 showed high photocatalytic performance in Methyl Orange(MO)degradation under visible light.The best sample presented a degradation rate of 0.164 min^-1,which is 3.2 and 82 times as high as that of Bi4O5I2 and g-C3N4,respectively.The g-C3N4/Bi4O5I2 was characterized by X-ray powder diffractometer(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),Raman,X-ray photoelectron spectroscopy(XPS),ultraviolet-visible diffuse reflectance spectra(DRS),electrochemical impedance spectroscopy(EIS)and transient photocurrent response in order to explain the enhanced photoactivity.Results indicated that the decoration with a small amount of g-C3N4 influenced the specific surface area only slightly.Nevertheless,the capability for absorbing visible light was improved measurably,which was beneficial to the MO degradation.On top of that,a strong interaction between g-C3N4 and Bi4O5I2 was detected.This interplay promoted the formation of a favorable heterojunction structure and thereby enhanced the charge separation.Thus,the g-C3N4/Bi4O5I2 composite presented greater charge separation efficiency and much better photocatalytic performance than Bi4O5I2.Additionally,g-C3N4/Bi4O5I2 also presented high stability.·O2^- and holes were verified to be the main reactive species.展开更多
Sc^3＋-doped lithium manganese oxides were synthesized by solid-state reaction. The influences of doping element on structure, mean valence of manganese, and electrochemical performances were studied by X-ray diffract...Sc^3＋-doped lithium manganese oxides were synthesized by solid-state reaction. The influences of doping element on structure, mean valence of manganese, and electrochemical performances were studied by X-ray diffraction （XRD）, galvanostatic charge-discharge and cyclic voltammetric tests, and also electrochemical impedance spectroscopy （EIS）. XRD tests showed that doped lithium manganese oxides were pure spinel structure without other phases. Redox titration and visible spectrophotometry tests indicated that the mean valence of manganese in doped lithium manganese oxides was higher than that of pure one. LiSc0.02Mn1.9804 remained 92.9% of the initial specific discharge capacity after 50th cycle at a constant current of 50 m/g, and the reversibility of LiSc0.02Mn1.98O4 was improved in comparison with pure LiMn2O4 at 50 ℃. EIS indicated that film deposition on spinel particles was suppressed because of Sc^3＋ doping, and the charge transfer between the surface film and spinel particles with increasing temperature for Sc^3＋-doped materials became easier as compared with undoped one.展开更多
This study evaluated the mechanical properties and thermal properties of Al-12 vol%B4 C composite at elevated temperature strengthened with in situ Al2 O3 network.The composite was fabricated using powder metallurgy(P...This study evaluated the mechanical properties and thermal properties of Al-12 vol%B4 C composite at elevated temperature strengthened with in situ Al2 O3 network.The composite was fabricated using powder metallurgy(PM)with raw materials of fine atomized aluminum powders,and the associated microstructures were observed.At 350℃,the composite had ultimate tensile strength of UTS=137 MPa,yield strength of YS0.2=118 MPa,and elongation ofε=4%.Besides,the mechanical properties of the composite remained unchanged at 350℃after the long holding periods up to 1000 h.The excellent mechanical properties and thermal stability at 350℃were secured by in situ am-Al2O3 network that strengthened the grain boundaries.The interfacial debonding and brittle cracking of B4 C particles were the main fracture mechanisms of the composite.In addition,the influence of sintering temperature and rolling deformation on the microstructures and mechanical properties was studied.展开更多
A novel coprecipitation-reduction process has been proposed for preparing highly selective Cu/ZnO/Al 2O 3 catalysts for methanol synthesis from CO 2 hydrogenation. Compared to the catalysts prepared by the conventiona...A novel coprecipitation-reduction process has been proposed for preparing highly selective Cu/ZnO/Al 2O 3 catalysts for methanol synthesis from CO 2 hydrogenation. Compared to the catalysts prepared by the conventional method, the new catalysts prepared via the new method exhibit much higher BET surface area and pore size, much smaller crystallite size and higher catalytic activity and selectivity in CO 2 hydrogenation to methanol. It is also found that the molar ratio of Cu + to Cu 0 on the surface of the catalyst obtained by coprecipitation-reduction is much higher than that on the reduced catalyst obtained by the conventional method, which could be crucial for its high activity and selectivity for catalytic hydrogenation of CO 2 to methanol.展开更多
基金financially supported by National Undergraduate Training Program for Innovation and Entrepreneurship(Nos.201810345012 and 201810345051)
文摘A graphite carbon nitride(g-C3N4)modified Bi4O5I2 composite was successfully prepared insitu via the thermal treatment of a g-C3N4/Bi OI precursor at 400°C for 3 hr.The as-prepared g-C3N4/Bi4O5I2 showed high photocatalytic performance in Methyl Orange(MO)degradation under visible light.The best sample presented a degradation rate of 0.164 min^-1,which is 3.2 and 82 times as high as that of Bi4O5I2 and g-C3N4,respectively.The g-C3N4/Bi4O5I2 was characterized by X-ray powder diffractometer(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),Raman,X-ray photoelectron spectroscopy(XPS),ultraviolet-visible diffuse reflectance spectra(DRS),electrochemical impedance spectroscopy(EIS)and transient photocurrent response in order to explain the enhanced photoactivity.Results indicated that the decoration with a small amount of g-C3N4 influenced the specific surface area only slightly.Nevertheless,the capability for absorbing visible light was improved measurably,which was beneficial to the MO degradation.On top of that,a strong interaction between g-C3N4 and Bi4O5I2 was detected.This interplay promoted the formation of a favorable heterojunction structure and thereby enhanced the charge separation.Thus,the g-C3N4/Bi4O5I2 composite presented greater charge separation efficiency and much better photocatalytic performance than Bi4O5I2.Additionally,g-C3N4/Bi4O5I2 also presented high stability.·O2^- and holes were verified to be the main reactive species.
文摘Sc^3＋-doped lithium manganese oxides were synthesized by solid-state reaction. The influences of doping element on structure, mean valence of manganese, and electrochemical performances were studied by X-ray diffraction （XRD）, galvanostatic charge-discharge and cyclic voltammetric tests, and also electrochemical impedance spectroscopy （EIS）. XRD tests showed that doped lithium manganese oxides were pure spinel structure without other phases. Redox titration and visible spectrophotometry tests indicated that the mean valence of manganese in doped lithium manganese oxides was higher than that of pure one. LiSc0.02Mn1.9804 remained 92.9% of the initial specific discharge capacity after 50th cycle at a constant current of 50 m/g, and the reversibility of LiSc0.02Mn1.98O4 was improved in comparison with pure LiMn2O4 at 50 ℃. EIS indicated that film deposition on spinel particles was suppressed because of Sc^3＋ doping, and the charge transfer between the surface film and spinel particles with increasing temperature for Sc^3＋-doped materials became easier as compared with undoped one.
基金financially supported by Shenzhen Engineering Laboratory of Nuclear Materials and Service Safety。
文摘This study evaluated the mechanical properties and thermal properties of Al-12 vol%B4 C composite at elevated temperature strengthened with in situ Al2 O3 network.The composite was fabricated using powder metallurgy(PM)with raw materials of fine atomized aluminum powders,and the associated microstructures were observed.At 350℃,the composite had ultimate tensile strength of UTS=137 MPa,yield strength of YS0.2=118 MPa,and elongation ofε=4%.Besides,the mechanical properties of the composite remained unchanged at 350℃after the long holding periods up to 1000 h.The excellent mechanical properties and thermal stability at 350℃were secured by in situ am-Al2O3 network that strengthened the grain boundaries.The interfacial debonding and brittle cracking of B4 C particles were the main fracture mechanisms of the composite.In addition,the influence of sintering temperature and rolling deformation on the microstructures and mechanical properties was studied.
文摘A novel coprecipitation-reduction process has been proposed for preparing highly selective Cu/ZnO/Al 2O 3 catalysts for methanol synthesis from CO 2 hydrogenation. Compared to the catalysts prepared by the conventional method, the new catalysts prepared via the new method exhibit much higher BET surface area and pore size, much smaller crystallite size and higher catalytic activity and selectivity in CO 2 hydrogenation to methanol. It is also found that the molar ratio of Cu + to Cu 0 on the surface of the catalyst obtained by coprecipitation-reduction is much higher than that on the reduced catalyst obtained by the conventional method, which could be crucial for its high activity and selectivity for catalytic hydrogenation of CO 2 to methanol.
