The use of a Fe-based metal organic framework（MOF）, namely MIL-88B（Fe）, as active material for lithium ion batteries（LIBs） is reported for the first time in the present work. Fe-based MOF demonstrated high capac...The use of a Fe-based metal organic framework（MOF）, namely MIL-88B（Fe）, as active material for lithium ion batteries（LIBs） is reported for the first time in the present work. Fe-based MOF demonstrated high capacity, excellent cycling stability and rate performance when used as anode. A highly reversible capacity of 680 mAhg^（-1） after 500 cycles at a current density of 200 m A g^（-1） was obtained. In addition, Fe2O3 and Fe3O4/C composites were obtained from Fe-based MOFs through thermal treatment. Both Fe2O3 and Fe3O4/C composites demonstrated high capacity and excellent cycling stability.展开更多
AlGaN-based solid state UV emitters have many advantages over conventional UV sources. However, UV-LEDs still suffer from numerous challenges, including low quantum efficiency compared to their blue LED counterparts. ...AlGaN-based solid state UV emitters have many advantages over conventional UV sources. However, UV-LEDs still suffer from numerous challenges, including low quantum efficiency compared to their blue LED counterparts. One of the inherent reasons is a lack of carrier localization effect inside fully miscible AlGaN alloys. In the pursuit of phase separation and carrier localization inside the active region of AlGaN UV-LED, utilization of highly misoriented substrates proves to be useful, yet the carrier distribution and recombination mechanism in such structures has seldom been reported. In this paper, a UV-LED with step-bunched surface morphology was designed and fabricated, and the internal mechanism of high internal quantum efficiency was studied in detail. The correlation between microscale current distribution and surface morphology was provided, directly demonstrating that current prefers to flow through the step edges of the epitaxial layers. Experimental results were further supported by numerical simulation. It was found that efficient radiative recombination centers were formed in the inclined quantum well regions. A schematic three-dimensional energy band structure of the multiple quantum wells(MQWs) across the step was proposed and helps in further understanding the luminescence behavior of LEDs grown on misoriented substrates. Finally, a general principle to achieve carrier localization was proposed, which is valid for most ternary Ⅲ-Ⅴ semiconductors exhibiting phase separation.展开更多
This paper reported the facile preparation of pyrolytic carbon derived from spent coffee grounds and the evaluation of its electrochemical performance when used as anode in sodium-ion battery.X-ray diffraction analys...This paper reported the facile preparation of pyrolytic carbon derived from spent coffee grounds and the evaluation of its electrochemical performance when used as anode in sodium-ion battery.X-ray diffraction analysis,scanning electron microscope,Brunauer–Emmett–Teller were employed to characterize the structure of pyrolytic carbon.Electrochemical performances were tested by constant current charge–discharge,cyclic voltammetry and electrochemical impedance spectroscopy.Results showed that the pyrolytic carbon possess a porous structure(1–2 lm)and a specific surface area of 94.35 m2 g1.When used as anodes in sodium-ion batteries,a reversible capacity of 154.2 mA h g1 at a current density of 200 mA g1 after 50 cycles was obtained.Several electrolytes were evaluated and their electrochemical performances were compared.The result indicated that this material has excellent storage capacity and good cycling stability.Our method provided a preparation of pyrolytic carbon from environmentally friendly resources.展开更多
This work reports on a compositionally graded heterojunction for photovoltaic application by cooperating fluorine-doped carbon quantum dots(FCQDs in short)into the CsPbI_(2.5)Br_(0.5)inorganic perovskite layer.Using t...This work reports on a compositionally graded heterojunction for photovoltaic application by cooperating fluorine-doped carbon quantum dots(FCQDs in short)into the CsPbI_(2.5)Br_(0.5)inorganic perovskite layer.Using this CsPbI_(2.5)Br_(0.5)/FCQDs graded heterojunction in conjunction with low-temperature-processed carbon electrode,a power conversion efficiency of 13.53%for 1 cm^(2)all-inorganic perovskite solar cell can be achieved at AM 1.5G solar irradiation.To the best of our knowledge,this is one of the highest efficiency reported for carbon electrode based all-inorganic perovskite solar cells so far,and the first report of 1 cm^(2)carbon counter electrode based inorganic perovskite solar cell with PCE exceeding 13%.Moreover,the inorganic perovskite/carbon quantum dot graded heterojunction photovoltaics maintained over 90%of their initial efficiency after thermal aging at 85°for 1056 hours.This conception of constructing inorganic perovskite/FCQDs graded heterojunction offers a feasible pathway to develop efficient and stable photovoltaics for scale-up and practical applications.展开更多
基金This work was supported by the National Natural Science Foundation of China （No. 51222104） and the Fundamental Research Funds for the Central Universities.
基金the National Natural Science Foundation of China(Grant Nos.21303236,51602320 and 51472255)the Natural Science Foundation of Zhejiang Province(LR14E020004)+3 种基金the Ningbo Natural Science Foundation(2016A610275)the program for the Ningbo Municipal Science and Technology Innovative Research Team(2015B11002)Financial support from the Ningbo“3315 Plan”the Youth Innovation Promotion Association of Chinese Academy of Sciences is appreciated
文摘The use of a Fe-based metal organic framework（MOF）, namely MIL-88B（Fe）, as active material for lithium ion batteries（LIBs） is reported for the first time in the present work. Fe-based MOF demonstrated high capacity, excellent cycling stability and rate performance when used as anode. A highly reversible capacity of 680 mAhg^（-1） after 500 cycles at a current density of 200 m A g^（-1） was obtained. In addition, Fe2O3 and Fe3O4/C composites were obtained from Fe-based MOFs through thermal treatment. Both Fe2O3 and Fe3O4/C composites demonstrated high capacity and excellent cycling stability.
基金National Key Research and Development Program of China(2016YFB0400802)National Natural Science Foundation of China(61974149)+2 种基金Key Research and Development Program of Zhejiang Province(2019C01080,2020C01145)Science and Technology Innovation 2025 Major Project of Ningbo(2018B10088,2019B10121)Instrument Developing Project of the Chinese Academy of Sciences(YJKYYQ20190074)。
文摘AlGaN-based solid state UV emitters have many advantages over conventional UV sources. However, UV-LEDs still suffer from numerous challenges, including low quantum efficiency compared to their blue LED counterparts. One of the inherent reasons is a lack of carrier localization effect inside fully miscible AlGaN alloys. In the pursuit of phase separation and carrier localization inside the active region of AlGaN UV-LED, utilization of highly misoriented substrates proves to be useful, yet the carrier distribution and recombination mechanism in such structures has seldom been reported. In this paper, a UV-LED with step-bunched surface morphology was designed and fabricated, and the internal mechanism of high internal quantum efficiency was studied in detail. The correlation between microscale current distribution and surface morphology was provided, directly demonstrating that current prefers to flow through the step edges of the epitaxial layers. Experimental results were further supported by numerical simulation. It was found that efficient radiative recombination centers were formed in the inclined quantum well regions. A schematic three-dimensional energy band structure of the multiple quantum wells(MQWs) across the step was proposed and helps in further understanding the luminescence behavior of LEDs grown on misoriented substrates. Finally, a general principle to achieve carrier localization was proposed, which is valid for most ternary Ⅲ-Ⅴ semiconductors exhibiting phase separation.
基金the National Key Research and Development Program(Grant No.2016YFB0100106)the Youth Innovation Promotion Association,Chinese Academy of Sciences(2015239)for financial supports.
文摘This paper reported the facile preparation of pyrolytic carbon derived from spent coffee grounds and the evaluation of its electrochemical performance when used as anode in sodium-ion battery.X-ray diffraction analysis,scanning electron microscope,Brunauer–Emmett–Teller were employed to characterize the structure of pyrolytic carbon.Electrochemical performances were tested by constant current charge–discharge,cyclic voltammetry and electrochemical impedance spectroscopy.Results showed that the pyrolytic carbon possess a porous structure(1–2 lm)and a specific surface area of 94.35 m2 g1.When used as anodes in sodium-ion batteries,a reversible capacity of 154.2 mA h g1 at a current density of 200 mA g1 after 50 cycles was obtained.Several electrolytes were evaluated and their electrochemical performances were compared.The result indicated that this material has excellent storage capacity and good cycling stability.Our method provided a preparation of pyrolytic carbon from environmentally friendly resources.
基金supported by the National Key Research and Development Program of China[2018YFB1502900,2019YFE0101300]the National Natural Science Foundation of China[No.21975088]the National Natural Science Foundation of China Major International(Regional)Joint Research Project[NO.51961165106].
文摘This work reports on a compositionally graded heterojunction for photovoltaic application by cooperating fluorine-doped carbon quantum dots(FCQDs in short)into the CsPbI_(2.5)Br_(0.5)inorganic perovskite layer.Using this CsPbI_(2.5)Br_(0.5)/FCQDs graded heterojunction in conjunction with low-temperature-processed carbon electrode,a power conversion efficiency of 13.53%for 1 cm^(2)all-inorganic perovskite solar cell can be achieved at AM 1.5G solar irradiation.To the best of our knowledge,this is one of the highest efficiency reported for carbon electrode based all-inorganic perovskite solar cells so far,and the first report of 1 cm^(2)carbon counter electrode based inorganic perovskite solar cell with PCE exceeding 13%.Moreover,the inorganic perovskite/carbon quantum dot graded heterojunction photovoltaics maintained over 90%of their initial efficiency after thermal aging at 85°for 1056 hours.This conception of constructing inorganic perovskite/FCQDs graded heterojunction offers a feasible pathway to develop efficient and stable photovoltaics for scale-up and practical applications.
