Xylan is the most abundant hemicellulose in nature. As a new type of green organic solvent, ionic liquid shows good preservation ability for the functional groups of hemicellulose. In this paper, a single molecule det...Xylan is the most abundant hemicellulose in nature. As a new type of green organic solvent, ionic liquid shows good preservation ability for the functional groups of hemicellulose. In this paper, a single molecule detection technology based on glass nanopore was established to analyze xylan dissolved in ionic liquid. Arabino-xylan (AX) and beech xylan (BX) are respectively taken as the representatives of heterogeneous xylan and homogeneous xylan. Firstly, unmodified glass nanopore was used to detect the dissolved xylan in ionic liquid, and then poly(ethylene imine) (PEI) was used to modify the nanopore to change the surface charge in the nanopore and further enhance the interaction between the nanopore and the xylan molecule. It was found that before and after nanopore modification, at negative voltage and low positive voltage, AX didn't generate current blocking signal. On the contrary, BX didn't generate current blocking signal at positive voltage. This phenomenon may be due to the current disturbance driven by electrophoresis and electroosmosis of xylan molecules with weak negative charge. After statistics analysis, the current blocking signal of AX showed that the modified nanopore showed multiple peaks. It indicates that heterogeneous xylan and PEI modified nanopore had stronger interaction. The results show that the nanopore detection technology can show the structural difference of heterogenous branched chain and homogeneous straight chain based on the single characteristic current blocking signal and statistical information, providing a research basis for the structural analysis of water insoluble polysaccharides.展开更多
Multicomponent metal sulfides have been recognized as promising anode materials for lithium/sodiumion storage given their enticing theoretical capacities. However, the simplification of synthetic processes and the con...Multicomponent metal sulfides have been recognized as promising anode materials for lithium/sodiumion storage given their enticing theoretical capacities. However, the simplification of synthetic processes and the construction of heterogeneous interfaces of multimetal sulfides remain great challenges. Herein,a hierarchical 1T-MoS2/carbon nanosheet decorated Co1–xS/N-doped carbon(Co1–xS/NC@MoS2/C) hollow nanofiber was designed and constructed via a one-pot hydrothermal method using a cobalt-based coordination polymer nanofiber. This nanofiber can transform in-situ into conductive N-doped carbon hollow fibers embedded with active Co1–xS nanoparticles, enabling the epitaxial growth of MoS2 nanosheets.Consequently, the Co1–xS/NC@MoS2/C composites achieve exceptional lithium/sodium-ion storage performance. Compared to MoS2/C microspheres and Co1–xS/NC hollow nanofibers alone, the Co1–xS/NC@MoS2/C hollow nanofibers deliver higher discharge capacities(1085.9 mAh g^-1 for lithium-ion batteries(LIBs) and 748.5 mAh g^-1 for sodium-ion batteries(SIBs) at 100 mA g^-1), better capacity retention(910 mAh g^-1 for LIBs and 636.5 mAh g^-1 for SIBs after 150 cycles at 100 mA g^-1), and increased cycling stability(407.2 mAh g^-1 after 1000 cycles for SIBs at 1000 m A g^-1). Furthermore, the kinetic analysis shows that the lithium/sodium-ion storage processes of the Co1–xS/NC@MoS2/C electrode are mainly controlled by pseudocapacitance behavior. The excellent electrochemical properties can thus be ascribed to the synergy of the MoS2/C nanosheets with the enlarged interlayer spacing, good conductivity of the carbon layers, and the Co1–xS nanoparticles embedded in the hollow nanofibers with extensive reaction sites.展开更多
基金financially supported by the Key Project of Technological Innovation and Application Development of Chongqing(cstc2021jscx-dxwtBx0002)West Light Foundation of the Chinese Academy of Sciences(Grant No.E0296105).
文摘Xylan is the most abundant hemicellulose in nature. As a new type of green organic solvent, ionic liquid shows good preservation ability for the functional groups of hemicellulose. In this paper, a single molecule detection technology based on glass nanopore was established to analyze xylan dissolved in ionic liquid. Arabino-xylan (AX) and beech xylan (BX) are respectively taken as the representatives of heterogeneous xylan and homogeneous xylan. Firstly, unmodified glass nanopore was used to detect the dissolved xylan in ionic liquid, and then poly(ethylene imine) (PEI) was used to modify the nanopore to change the surface charge in the nanopore and further enhance the interaction between the nanopore and the xylan molecule. It was found that before and after nanopore modification, at negative voltage and low positive voltage, AX didn't generate current blocking signal. On the contrary, BX didn't generate current blocking signal at positive voltage. This phenomenon may be due to the current disturbance driven by electrophoresis and electroosmosis of xylan molecules with weak negative charge. After statistics analysis, the current blocking signal of AX showed that the modified nanopore showed multiple peaks. It indicates that heterogeneous xylan and PEI modified nanopore had stronger interaction. The results show that the nanopore detection technology can show the structural difference of heterogenous branched chain and homogeneous straight chain based on the single characteristic current blocking signal and statistical information, providing a research basis for the structural analysis of water insoluble polysaccharides.
基金This work was supported by the National Natural Science Foundation of China(51673117,21805193 and 51973118)Postdoctoral Science Foundation of China(2019M650212)+2 种基金Key R&D Program of Guangdong Province(2019B010929002 and 2019B010941001)Science and Technology Innovation Commission of Shenzhen(JCYJ20170817094628397,JCYJ20170818093832350,JCYJ20170818112409808,JCYJ20170818100112531,JCYJ20180507184711069,and JCYJ20180305125319991)The authors also thank the Materials and Devices Testing Center of Tsinghua University Shenzhen Graduate School.
文摘Multicomponent metal sulfides have been recognized as promising anode materials for lithium/sodiumion storage given their enticing theoretical capacities. However, the simplification of synthetic processes and the construction of heterogeneous interfaces of multimetal sulfides remain great challenges. Herein,a hierarchical 1T-MoS2/carbon nanosheet decorated Co1–xS/N-doped carbon(Co1–xS/NC@MoS2/C) hollow nanofiber was designed and constructed via a one-pot hydrothermal method using a cobalt-based coordination polymer nanofiber. This nanofiber can transform in-situ into conductive N-doped carbon hollow fibers embedded with active Co1–xS nanoparticles, enabling the epitaxial growth of MoS2 nanosheets.Consequently, the Co1–xS/NC@MoS2/C composites achieve exceptional lithium/sodium-ion storage performance. Compared to MoS2/C microspheres and Co1–xS/NC hollow nanofibers alone, the Co1–xS/NC@MoS2/C hollow nanofibers deliver higher discharge capacities(1085.9 mAh g^-1 for lithium-ion batteries(LIBs) and 748.5 mAh g^-1 for sodium-ion batteries(SIBs) at 100 mA g^-1), better capacity retention(910 mAh g^-1 for LIBs and 636.5 mAh g^-1 for SIBs after 150 cycles at 100 mA g^-1), and increased cycling stability(407.2 mAh g^-1 after 1000 cycles for SIBs at 1000 m A g^-1). Furthermore, the kinetic analysis shows that the lithium/sodium-ion storage processes of the Co1–xS/NC@MoS2/C electrode are mainly controlled by pseudocapacitance behavior. The excellent electrochemical properties can thus be ascribed to the synergy of the MoS2/C nanosheets with the enlarged interlayer spacing, good conductivity of the carbon layers, and the Co1–xS nanoparticles embedded in the hollow nanofibers with extensive reaction sites.
