Metal oxide anode material is one of promising candidates for the next-generation LIBs, due to its high theoretical capacity and low cost. The poor conductivity and huge volume change during charge/ discharge, however...Metal oxide anode material is one of promising candidates for the next-generation LIBs, due to its high theoretical capacity and low cost. The poor conductivity and huge volume change during charge/ discharge, however, restrict the commercialization of metal oxide anode material. In this work, we design a novel Cu-SnO2 composite derived from Cu6Sn5 alloy with three dimensional （3D） metal cluster conducting architecture. The novel Cu structure penetrates in the composite particles inducing high conductivity and space-confined SnO2, which restrict the pulverization of SnO2 during lithiation/ delithiation process. The optimized Cu-SnO2 composite anode delivers an initial discharge capacity of 933.7 mA h/g and retains a capacity of 536.1 mA h/g after 200 cycles, at 25℃ and a rate of 100 mA/g. Even at the high rate of 300 mA/g, the anode still exhibits a capacity of more than 29% of that tested at 50 mA/g. Combining with the phase and morphology analysis, the novel Cu-SnO2 composite not only has good electrical conductivity, but also possesses high theoretical capacity （995 mAh/g）, which may pave a new way for the design and construction of next-generation metal oxide anode materials with high power and cycling stability.展开更多
A novel chemical technique combined with unique plasma activated sintering（PAS） was utilized to prepare consolidated copper matrix composites（CMCs） by adding Cu-SnO2-rGO layered micro powders as reinforced fillers...A novel chemical technique combined with unique plasma activated sintering（PAS） was utilized to prepare consolidated copper matrix composites（CMCs） by adding Cu-SnO2-rGO layered micro powders as reinforced fillers into Cu matrix. The repeating Cu-SnO2-rGO structure was composed of inner dispersed reduced graphene oxide（r GO）, SnO2 as intermedia and outer Cu coating. SnO2 was introduced to the surface of rGO sheets in order to prevent the graphene aggregation with SnO2 serving as spacer and to provide enough active sites for subsequent Cu deposition. This process can guarantee rGO sheets to suffi ciently disperse and Cu nanoparticles to tightly and uniformly anchor on each layer of rGO by means of the SnO2 active sites as well as strictly control the reduction speed of Cu^2＋. The complete cover of Cu nanoparticles on rGO sheets thoroughly avoids direct contact among rGO layers. Hence, the repeating structure can simultaneously solve the wettability problem between rGO and Cu matrix as well as improve the bonding strength between rGO and Cu matrix at the well-bonded Cu-SnO2-rGO interface. The isolated rGO can effectively hinder the glide of dislocation at Cu-rGO interface and support the applied loads. Finally, the compressive strength of CMCs was enhanced when the strengthening effi ciency reached up to 41.展开更多
Zn-Cu-codoped SnO2 nanoparticles have been synthesized by chemical precipitation method. All nanoparticles are crystalline, with the average size increases from 2.55 nm to 4.13 nm as the calcination temperature increa...Zn-Cu-codoped SnO2 nanoparticles have been synthesized by chemical precipitation method. All nanoparticles are crystalline, with the average size increases from 2.55 nm to 4.13 nm as the calcination temperature increases from 400℃ to 600℃. The high calcination temperature can enhance the crystalline quality and grain growth. The oxygen content decreases with decreasing calcination temperature; at a low temperature of 400℃, Zn-Cu-codoped SnO2 nanoparticles are in a rather oxygen-poor state having many oxygen vacancies. The optical band gap energies of Zn-Cu-codoped SnO2 nanoparticles calcined at 400℃ and 600℃ are decreased from 3.93 eV to 3.62 eV due to quantum confinement effects. Both samples exhibit room-temperature ferromagnetism, with a larger saturation magnetization at 400℃ due to the presence of large density of defects such as oxygen vacancies. Zn-Cu-codoped SnO2 nanoparticles exhibit large optical band gap energies and room temperature ferromagnetism, which make them potential candidates for applications in optoelectronics and spintronics.展开更多
To understand the effect of the doping amount of Cu^2+ on the structure and reactivity of SnO2 in NOx-SCR with NH3, a series of Sn-Cu-O binary oxide catalysts with different Sn/Cu ratios have been prepared and thoroug...To understand the effect of the doping amount of Cu^2+ on the structure and reactivity of SnO2 in NOx-SCR with NH3, a series of Sn-Cu-O binary oxide catalysts with different Sn/Cu ratios have been prepared and thoroughly characterized. Using the XRD extrapolation method, the SnO2 lattice capacity for Cu^2+ cations is determined at 0.10 g Cu O per g of SnO2, equaling a Sn/Cu molar ratio of 84/16. Therefore, in a tetragonal rutile SnO2 lattice, only a maximum of 16% of the Sn4+ cations can be replaced by Cu^2+ to form a stable solid solution structure. If the Cu content is higher, Cu O will form on the catalyst surface, which has a negative effect on the reaction performance. For samples in a pure solid solution phase, the number of surface defects increase with increasing Cu content until it reaches the lattice capacity, as confirmed by Raman spectroscopy. As a result, the amounts of both active oxygen species and acidic sites on the surface, which critically determine the reaction performance, also increase and reach the maximum level for the catalyst with a Cu content close to the lattice capacity. A distinct lattice capacity threshold effect on the structure and reactivity of Sn-Cu binary oxide catalysts has been observed. A Sn-Cu catalyst with the best reaction performance can be obtained by doping the SnO2 matrix with the lattice capacity amount of Cu^2+.展开更多
基金financial supports for this research from the Natural Science Foundation of Tianjin (No. 16JCYBJC41700)Tianjin Major Program of New Materials Science and Technology (Nos. 16ZXCLGX00070, 16ZXCLGX00110)+2 种基金Tianjin Municipal Education Committee Scientific Research Projects (No. 2017KJ075)the National Nature Science Foundation of China (No. 21676200)Key Laboratory of Advanced Ceramics and Machining Technology, Ministry of Education (Tianjin University)
文摘Metal oxide anode material is one of promising candidates for the next-generation LIBs, due to its high theoretical capacity and low cost. The poor conductivity and huge volume change during charge/ discharge, however, restrict the commercialization of metal oxide anode material. In this work, we design a novel Cu-SnO2 composite derived from Cu6Sn5 alloy with three dimensional （3D） metal cluster conducting architecture. The novel Cu structure penetrates in the composite particles inducing high conductivity and space-confined SnO2, which restrict the pulverization of SnO2 during lithiation/ delithiation process. The optimized Cu-SnO2 composite anode delivers an initial discharge capacity of 933.7 mA h/g and retains a capacity of 536.1 mA h/g after 200 cycles, at 25℃ and a rate of 100 mA/g. Even at the high rate of 300 mA/g, the anode still exhibits a capacity of more than 29% of that tested at 50 mA/g. Combining with the phase and morphology analysis, the novel Cu-SnO2 composite not only has good electrical conductivity, but also possesses high theoretical capacity （995 mAh/g）, which may pave a new way for the design and construction of next-generation metal oxide anode materials with high power and cycling stability.
基金Funded by the National Natural Science Foundation of China(51572208)the 111 Project(B13035)+1 种基金the National Natural Science Foundation of Hubei Province(2014CFB257 and 2014CFB258)the Fundamental Research Funds for the Central Universities(WUT:2015-III-059)
文摘A novel chemical technique combined with unique plasma activated sintering（PAS） was utilized to prepare consolidated copper matrix composites（CMCs） by adding Cu-SnO2-rGO layered micro powders as reinforced fillers into Cu matrix. The repeating Cu-SnO2-rGO structure was composed of inner dispersed reduced graphene oxide（r GO）, SnO2 as intermedia and outer Cu coating. SnO2 was introduced to the surface of rGO sheets in order to prevent the graphene aggregation with SnO2 serving as spacer and to provide enough active sites for subsequent Cu deposition. This process can guarantee rGO sheets to suffi ciently disperse and Cu nanoparticles to tightly and uniformly anchor on each layer of rGO by means of the SnO2 active sites as well as strictly control the reduction speed of Cu^2＋. The complete cover of Cu nanoparticles on rGO sheets thoroughly avoids direct contact among rGO layers. Hence, the repeating structure can simultaneously solve the wettability problem between rGO and Cu matrix as well as improve the bonding strength between rGO and Cu matrix at the well-bonded Cu-SnO2-rGO interface. The isolated rGO can effectively hinder the glide of dislocation at Cu-rGO interface and support the applied loads. Finally, the compressive strength of CMCs was enhanced when the strengthening effi ciency reached up to 41.
基金Project supported by the Natural Science Foundation of Zhejiang Province,China(Grant No.LR16F040001)
文摘Zn-Cu-codoped SnO2 nanoparticles have been synthesized by chemical precipitation method. All nanoparticles are crystalline, with the average size increases from 2.55 nm to 4.13 nm as the calcination temperature increases from 400℃ to 600℃. The high calcination temperature can enhance the crystalline quality and grain growth. The oxygen content decreases with decreasing calcination temperature; at a low temperature of 400℃, Zn-Cu-codoped SnO2 nanoparticles are in a rather oxygen-poor state having many oxygen vacancies. The optical band gap energies of Zn-Cu-codoped SnO2 nanoparticles calcined at 400℃ and 600℃ are decreased from 3.93 eV to 3.62 eV due to quantum confinement effects. Both samples exhibit room-temperature ferromagnetism, with a larger saturation magnetization at 400℃ due to the presence of large density of defects such as oxygen vacancies. Zn-Cu-codoped SnO2 nanoparticles exhibit large optical band gap energies and room temperature ferromagnetism, which make them potential candidates for applications in optoelectronics and spintronics.
文摘To understand the effect of the doping amount of Cu^2+ on the structure and reactivity of SnO2 in NOx-SCR with NH3, a series of Sn-Cu-O binary oxide catalysts with different Sn/Cu ratios have been prepared and thoroughly characterized. Using the XRD extrapolation method, the SnO2 lattice capacity for Cu^2+ cations is determined at 0.10 g Cu O per g of SnO2, equaling a Sn/Cu molar ratio of 84/16. Therefore, in a tetragonal rutile SnO2 lattice, only a maximum of 16% of the Sn4+ cations can be replaced by Cu^2+ to form a stable solid solution structure. If the Cu content is higher, Cu O will form on the catalyst surface, which has a negative effect on the reaction performance. For samples in a pure solid solution phase, the number of surface defects increase with increasing Cu content until it reaches the lattice capacity, as confirmed by Raman spectroscopy. As a result, the amounts of both active oxygen species and acidic sites on the surface, which critically determine the reaction performance, also increase and reach the maximum level for the catalyst with a Cu content close to the lattice capacity. A distinct lattice capacity threshold effect on the structure and reactivity of Sn-Cu binary oxide catalysts has been observed. A Sn-Cu catalyst with the best reaction performance can be obtained by doping the SnO2 matrix with the lattice capacity amount of Cu^2+.
