Hongjun Fu

Enhancing Dielectric Properties of Poly(vinylidene fluoride)-Based Hybrid Nanocomposites by Synergic Employment of Hydroxylated BaTiO3 and Silanized Graphene

ABSTRACT The poly(vinylidene fluoride)-based hybrid composites with a blended BaTiO3–exfoliated graphene as filler were fabricated with the efficient method of solution casting and hot pressing and their dielectric properties were investigated in detail. In advance, both of the nanoparticles are functionalized to improve the interfacial bonding between fillers and matrix. Synergistic effects arising from blending zero-dimensional BaTiO3 and two-dimensional exfoliated grapheneare identified by the improved distribution of nanoparticles in poly(vinylidene fluoride) host and mitigating the concomitant increase in dielectric loss while maintaining the high dielectric constant values of the composites. GRAPHICAL ABSTRACT

TiO2 seeded on nitrogen-doped porous carbon nanofibers for superior electrochemical performance as freestanding anodes of lithium-ion batteries

Fibrous mats piled by nitrogen-doped porous carbon nanofibers with seeded TiO2 are fabricated and punched directly into circles as lithium-ion battery anodes. The seeding structure is composed of semi-wrapped TiO2 nanoparticles on carbon nanofibers (CNFs) coated with a thin layer of carbon. Synchronously, pores with various widths are formed on CNFs. As a freestanding anode, an initial discharge capacity of 615 mAh g-1 with a coulombic efficiency of 56% is reached, and 322 mAh g-1 is obtained after 100 cycles at a current density of 100 mA g-1. This is assigned to the increasing number of active sites for the lithium ion from pores with various widths and improved conductivity originating from nitrogen doping. Superior rate performance (179 mAh g-1 at the current density of 2000 mA g-1) under various current densities compared with that of other counterparts is attributed to the structural stability originating from the seeding structure with the help of the C-O-Ti bond. An additional 800 cycles are displayed at the current density of 2000 mA g-1, and superior stability is also exhibited.