Two-dimensional(2D)materials with tunable electronic transitions are vital for next-generation electronics and energy storage technologies.Here,we demonstrate a novel,thermally-driven,reversible modulation of electron...Two-dimensional(2D)materials with tunable electronic transitions are vital for next-generation electronics and energy storage technologies.Here,we demonstrate a novel,thermally-driven,reversible modulation of electronic conductivity in the quaternary heteroanionic 2D van der Waals superlattice Bi_(4)O_(4)SeCl_(2).Systematic thermal annealing of bulk Bi_(4)O_(4)SeCl_(2)induces a striking reversible transition from insulating to semiconducting behavior,accompanied by a 10~6 times magnitude enhancement in electrical conductivity.This dramatic transformation originates from thermally mediated defect annihilation and grain boundary elimination,substantially reducing carrier scattering barriers and enhancing intrinsic carrier concentration.Moreover,leveraging its intrinsic layered structure,we successfully exfoliated Bi_(4)O_(4)SeCl_(2)into nanosheets(~1.5 nm in thickness)and utilized these exfoliated layers as interfacial coatings on Zn electrodes,markedly improving dendrite suppression and extending the cycling stability of Zn-ion hybrid capacitors and Zn/MnO_(2)batteries.Our work elucidates crucial defect-driven micro s tructural mechanisms responsible for thermally-induced reversible electronic transitions,establishing heteroanionic Bi_(4)O_(4)SeCl_(2)as a promising platform for advanced electronic and energystorage materials engineering.展开更多
Conductive polyvinylidene fluoride（PVDF）matrix composites filled with graphited fiber（GF）or carbon fiber（CF）were prepared by the melt-mixing method.The breakage and length distribution of the fibers in the polym...Conductive polyvinylidene fluoride（PVDF）matrix composites filled with graphited fiber（GF）or carbon fiber（CF）were prepared by the melt-mixing method.The breakage and length distribution of the fibers in the polymer matrix were studied by scanning electron microscope（SEM）and optical microscope（OM）observations,respectively. The differences in the positive temperature coefficient（PTC）effects of the composites were mainly attributed to inter-fiber contact ability.The elimination of the negative temperature coefficient（NTC）effect for CF/PVDF composite was because of an increase in the viscosity of the polymer matrix.With the same filler content,CF could be more effective,to eliminate the NTC effect when compared with GF.Addition of 2%CF（mass fraction）in the PVDF composite with 7%GF（mass fraction）could effectively eliminate the NTC phenomenon of the composite.展开更多
The dispersing process of polyacenic semiconductor(PAS) in polyethylene(PE) was simulated by using molecular dynamics(MD) methods. The results show that this process can be divided into three stages. In the first stag...The dispersing process of polyacenic semiconductor(PAS) in polyethylene(PE) was simulated by using molecular dynamics(MD) methods. The results show that this process can be divided into three stages. In the first stage, PAS particles in the crystal region of PE are expelled to the amorphous region; in the second stage, PAS particles aggregate due to small surface areas and PE chains are adjusted continuously, which makes the crystal region complete; PAS particles are separated from each other and the total energy increases in the third stage. During the whole dispersing process, PAS particles are more stable in the amorphous region than in the crystal region. All the simulation results are in good agreement with the experimental results.展开更多
基金supported by the National Key Research and Development Program of China(No.2021YFA1200903)National Natural Science Foundation of China(Nos.22175203,22006023,and 11974435)+1 种基金Natural Science Foundation of Guangdong Province(Nos.2022B1515020065 and 2020A1515110821,2023A1515010841,2025A1515010050)Guangzhou Science and Technology Project(No.202102020126)
文摘Two-dimensional(2D)materials with tunable electronic transitions are vital for next-generation electronics and energy storage technologies.Here,we demonstrate a novel,thermally-driven,reversible modulation of electronic conductivity in the quaternary heteroanionic 2D van der Waals superlattice Bi_(4)O_(4)SeCl_(2).Systematic thermal annealing of bulk Bi_(4)O_(4)SeCl_(2)induces a striking reversible transition from insulating to semiconducting behavior,accompanied by a 10~6 times magnitude enhancement in electrical conductivity.This dramatic transformation originates from thermally mediated defect annihilation and grain boundary elimination,substantially reducing carrier scattering barriers and enhancing intrinsic carrier concentration.Moreover,leveraging its intrinsic layered structure,we successfully exfoliated Bi_(4)O_(4)SeCl_(2)into nanosheets(~1.5 nm in thickness)and utilized these exfoliated layers as interfacial coatings on Zn electrodes,markedly improving dendrite suppression and extending the cycling stability of Zn-ion hybrid capacitors and Zn/MnO_(2)batteries.Our work elucidates crucial defect-driven micro s tructural mechanisms responsible for thermally-induced reversible electronic transitions,establishing heteroanionic Bi_(4)O_(4)SeCl_(2)as a promising platform for advanced electronic and energystorage materials engineering.
基金the National Natural Science Foundation of China(Nos.20771030 and 20671025).
文摘Conductive polyvinylidene fluoride（PVDF）matrix composites filled with graphited fiber（GF）or carbon fiber（CF）were prepared by the melt-mixing method.The breakage and length distribution of the fibers in the polymer matrix were studied by scanning electron microscope（SEM）and optical microscope（OM）observations,respectively. The differences in the positive temperature coefficient（PTC）effects of the composites were mainly attributed to inter-fiber contact ability.The elimination of the negative temperature coefficient（NTC）effect for CF/PVDF composite was because of an increase in the viscosity of the polymer matrix.With the same filler content,CF could be more effective,to eliminate the NTC effect when compared with GF.Addition of 2%CF（mass fraction）in the PVDF composite with 7%GF（mass fraction）could effectively eliminate the NTC phenomenon of the composite.
文摘The dispersing process of polyacenic semiconductor(PAS) in polyethylene(PE) was simulated by using molecular dynamics(MD) methods. The results show that this process can be divided into three stages. In the first stage, PAS particles in the crystal region of PE are expelled to the amorphous region; in the second stage, PAS particles aggregate due to small surface areas and PE chains are adjusted continuously, which makes the crystal region complete; PAS particles are separated from each other and the total energy increases in the third stage. During the whole dispersing process, PAS particles are more stable in the amorphous region than in the crystal region. All the simulation results are in good agreement with the experimental results.
