Constructing heterostructures is an important approach to develop high-performance anode materials for sodium ion batteries(SIBs).The abundant phase interfaces provide numerous defects and active sites for rapid elect...Constructing heterostructures is an important approach to develop high-performance anode materials for sodium ion batteries(SIBs).The abundant phase interfaces provide numerous defects and active sites for rapid electron/ion transport.Herein,CoSe_(2)■NC@NC/MoS_(2) heterostructures are prepared through a multi-step reaction strategy,CoSe_(2) nanoparticles served as the coating shells for MoS_(2) cores are anchored in carbon frameworks.The core–shell structure effectively buffers the double volume expansion and inhibits the dissolution of MoS_(2) and CoSe_(2) in the electrolyte.AsSIBs anodes,the heterostructure delivers a high reversible capacity of 481.6 m Ah g^(-1) at 0.5 A g^(-1) after 100 cycles,superior rate capability(174.5 m Ah g^(-1) at 20.0 A g^(-1)),excellent long-term cycle performance(333.4 m Ah g^(-1) after 2000 cycles at 5.0 A g^(-1)).The DFT calculation proves that the electronic distribution of heterostructures is reconstructed with enhanced conductivity.The kinetic analysis,mechanism characterizations and full-cells tests exhibit the synergistic reaction mechanism among different components and practical application prospects.The heterostructure also shows more rapid ions diffusion kinetics than single components.展开更多
It is challenging to prepare a binary assembled metal-organic framework(MOF) by anisotropic epitaxial growth method. Besides, nanocages(NCs) with hollow structures are often constructed to improve microwave absorbing ...It is challenging to prepare a binary assembled metal-organic framework(MOF) by anisotropic epitaxial growth method. Besides, nanocages(NCs) with hollow structures are often constructed to improve microwave absorbing abilities. Herein, we combine the selective epitaxial growth and hollow engineering technologies to fabricate hybrid MOF-derived NCs. Benefiting from the unique nanocage/porous structure,complementary magnetic/dielectric components and suitable impedance matching characteristics, the optimized absorber(CoNi/TiO@PC-NCs) exhibits unique microwave absorbing properties. It is worth noting that the minimum reflection loss(RLmin) of the absorber reaches-65.3 dB, and the overall effective absorption bandwidth(EAB, RL <-10 dB) covers 15.1 GHz(2.9–18 GHz). The maximum EAB under a single thickness covers 4.4 GHz, displaying skipping dual-band coverages at both high and low frequencies. This work might provide a novel perspective for the synthesis of assembled MOF-derived absorbers.展开更多
基金financially supported by the National Natural Science Foundation of China(21975206,21901206)。
文摘Constructing heterostructures is an important approach to develop high-performance anode materials for sodium ion batteries(SIBs).The abundant phase interfaces provide numerous defects and active sites for rapid electron/ion transport.Herein,CoSe_(2)■NC@NC/MoS_(2) heterostructures are prepared through a multi-step reaction strategy,CoSe_(2) nanoparticles served as the coating shells for MoS_(2) cores are anchored in carbon frameworks.The core–shell structure effectively buffers the double volume expansion and inhibits the dissolution of MoS_(2) and CoSe_(2) in the electrolyte.AsSIBs anodes,the heterostructure delivers a high reversible capacity of 481.6 m Ah g^(-1) at 0.5 A g^(-1) after 100 cycles,superior rate capability(174.5 m Ah g^(-1) at 20.0 A g^(-1)),excellent long-term cycle performance(333.4 m Ah g^(-1) after 2000 cycles at 5.0 A g^(-1)).The DFT calculation proves that the electronic distribution of heterostructures is reconstructed with enhanced conductivity.The kinetic analysis,mechanism characterizations and full-cells tests exhibit the synergistic reaction mechanism among different components and practical application prospects.The heterostructure also shows more rapid ions diffusion kinetics than single components.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.21975206 and 21901206)the Foundation of Shaanxi Province Natural Science Basic Research Program(No.2020JQ-146)the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University。
文摘It is challenging to prepare a binary assembled metal-organic framework(MOF) by anisotropic epitaxial growth method. Besides, nanocages(NCs) with hollow structures are often constructed to improve microwave absorbing abilities. Herein, we combine the selective epitaxial growth and hollow engineering technologies to fabricate hybrid MOF-derived NCs. Benefiting from the unique nanocage/porous structure,complementary magnetic/dielectric components and suitable impedance matching characteristics, the optimized absorber(CoNi/TiO@PC-NCs) exhibits unique microwave absorbing properties. It is worth noting that the minimum reflection loss(RLmin) of the absorber reaches-65.3 dB, and the overall effective absorption bandwidth(EAB, RL <-10 dB) covers 15.1 GHz(2.9–18 GHz). The maximum EAB under a single thickness covers 4.4 GHz, displaying skipping dual-band coverages at both high and low frequencies. This work might provide a novel perspective for the synthesis of assembled MOF-derived absorbers.
