The preparation of nanometer γ-Fe2O3 through an electrochemical process was studied at room temperature, using a metal iron plate as sacrificing anode and a sheet of stainless steel as cathode, in non-aqueous mediate...The preparation of nanometer γ-Fe2O3 through an electrochemical process was studied at room temperature, using a metal iron plate as sacrificing anode and a sheet of stainless steel as cathode, in non-aqueous mediate containing （Bu）4 NBr as support electrolyre and 2% （vol%） water. The powdery particles obtained were then calcined at 300 ℃. The products were characterized by IR, XRD, SEM, TEM and laser particle size analyser, indicating the fine particle is a pure nanometer γ-Fe2O3. The morphology is like coneshaped and their average size is 22.0 nm. Furthermore the VSM spectrum shows that the particle＇s coercivity （3.9 × 10^3 A/m） is rather small, presenting the excellent super-paramagnetism.展开更多
As next-generation photovoltaic devices,methylammonium lead iodide(MAPbI_(3))-based organic-inorganic halide perovskite solar cells(PSCs)have received considerable attention because of their cost effectiveness and hig...As next-generation photovoltaic devices,methylammonium lead iodide(MAPbI_(3))-based organic-inorganic halide perovskite solar cells(PSCs)have received considerable attention because of their cost effectiveness and high efficiency.However,their practical applications are retarded due to severe instability under moisture,thermal and sunlight conditions,which are closely related to the insufficient perovskite film quality and high photocatalytic activity of defective TiO_(2) electron-transporting layer(ETL)to accelerate the perovskite decomposition.Herein,remarkably enhanced power conversion efficiency(PCE)and stability of MAPbI_(3)-based PSCs is reached through the use of a new sodium fluoride(NaF)sacrificing layer,which,introduced between the perovskite layer and ETL,is sacrificed during cell fabrication by penetrating into the perovskite layer,improving the perovskite film quality,while partial NaF is incorporated into the mesoporous TiO_(2) ETL during NaF layer fabrication to passivate TiO_(2) and construct a well-matched energy level alignment.As a result,the optimized PSC generates a high PCE of 20.9%,which is 17%higher than that of the pristine cell(17.9%),and outstanding performance stability due to remarkably enhanced moisture,thermal and sunlight stability.This study highlights a simple and effective approach to boost the PCE and durability of MAPbI 3-based PSCs simultaneously,accelerating the commercialization of this technology.展开更多
In the spring of 1999, the Xi'an Tang City Archaeological Team, IA, CASS, excavated the ruined round altar at Tang Chang' an city. The round altar was the ritual building where the emperor sacrificed to Heaven...In the spring of 1999, the Xi'an Tang City Archaeological Team, IA, CASS, excavated the ruined round altar at Tang Chang' an city. The round altar was the ritual building where the emperor sacrificed to Heaven. Lying in the east of the southern suburbs of Tang Chang' an city, it was constructed in the Sui and abandoned at the end of the Tang period. As known from the ruins, it was an open-air building with four tiers of circular platforms, each measuring about 2m in height and having in the periphery 12 flights of ascending steps to symbolize the 12 two-hour periods of the day. The whole altar is constructed of rammed yellow earth and covered with a layer of white plaster. Its excavation furnishes material evidence to the literary records on ceremonies of sacrificing to Heaven in the Tang period and provides firsthand sources for studying the evolution and historical role of the ancient Chinese ritual system.展开更多
文摘The preparation of nanometer γ-Fe2O3 through an electrochemical process was studied at room temperature, using a metal iron plate as sacrificing anode and a sheet of stainless steel as cathode, in non-aqueous mediate containing （Bu）4 NBr as support electrolyre and 2% （vol%） water. The powdery particles obtained were then calcined at 300 ℃. The products were characterized by IR, XRD, SEM, TEM and laser particle size analyser, indicating the fine particle is a pure nanometer γ-Fe2O3. The morphology is like coneshaped and their average size is 22.0 nm. Furthermore the VSM spectrum shows that the particle＇s coercivity （3.9 × 10^3 A/m） is rather small, presenting the excellent super-paramagnetism.
基金supported by the National Natural Science Foundation of China(Nos.21908106 and 21878158)the Jiangsu Natural Science Foundation(No.BK20190682)+1 种基金the Program for Jiangsu Specially-Appointed Professors,the Funding from State Key Laboratory of Materials-Oriented Chemical Engineering(No.ZK201808)a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘As next-generation photovoltaic devices,methylammonium lead iodide(MAPbI_(3))-based organic-inorganic halide perovskite solar cells(PSCs)have received considerable attention because of their cost effectiveness and high efficiency.However,their practical applications are retarded due to severe instability under moisture,thermal and sunlight conditions,which are closely related to the insufficient perovskite film quality and high photocatalytic activity of defective TiO_(2) electron-transporting layer(ETL)to accelerate the perovskite decomposition.Herein,remarkably enhanced power conversion efficiency(PCE)and stability of MAPbI_(3)-based PSCs is reached through the use of a new sodium fluoride(NaF)sacrificing layer,which,introduced between the perovskite layer and ETL,is sacrificed during cell fabrication by penetrating into the perovskite layer,improving the perovskite film quality,while partial NaF is incorporated into the mesoporous TiO_(2) ETL during NaF layer fabrication to passivate TiO_(2) and construct a well-matched energy level alignment.As a result,the optimized PSC generates a high PCE of 20.9%,which is 17%higher than that of the pristine cell(17.9%),and outstanding performance stability due to remarkably enhanced moisture,thermal and sunlight stability.This study highlights a simple and effective approach to boost the PCE and durability of MAPbI 3-based PSCs simultaneously,accelerating the commercialization of this technology.
文摘In the spring of 1999, the Xi'an Tang City Archaeological Team, IA, CASS, excavated the ruined round altar at Tang Chang' an city. The round altar was the ritual building where the emperor sacrificed to Heaven. Lying in the east of the southern suburbs of Tang Chang' an city, it was constructed in the Sui and abandoned at the end of the Tang period. As known from the ruins, it was an open-air building with four tiers of circular platforms, each measuring about 2m in height and having in the periphery 12 flights of ascending steps to symbolize the 12 two-hour periods of the day. The whole altar is constructed of rammed yellow earth and covered with a layer of white plaster. Its excavation furnishes material evidence to the literary records on ceremonies of sacrificing to Heaven in the Tang period and provides firsthand sources for studying the evolution and historical role of the ancient Chinese ritual system.
