Mingzhi Wei

Graphene membrane encapsulated Co3O4 nanotubes with superior capacity and stability as anode materials for lithium ion batteries

The electrospun Co3O4 nanotubes encapsulated by graphene membrane are successfully synthesized via a novel and efficient method. The Co3O4 nanotubes with the diameter of ~200u2009nm are prepared by electrospinning combined with sintering process. Graphene is wrapped on the charge-modified surface of Co3O4 nanotubes by the mutual electrostatic interactions. The as-prepared graphene/Co3O4 nanotubes are applied as anode materials for lithium-ion batteries and show the improved rate capacities (up to 430.9u2009mAh g−1 at the current density of 1600u2009mA g−1) and excellent rechargeable stability (961.4u2009mAh g−1 at the current density of 100u2009mA g−1 after 80 cycles). The existence of graphene membrane not only decreases the lithium ion transport path due to serving as the additional transport channel, but also provides the elastic buffer to avoid the agglomeration of the Co3O4 nanotubes. The nanotubes located in the graphene could effectively prevent the agglomeration of graphene membranes, and consequently keep their high active surface area. The complementary and synergistic effect of Co3O4 nanotubes and graphene makes a great contribution to the outstanding electrochemical properties.Graphical AbstractThe graphene/Co3O4 nanotubes composites were applied as anode materials and shown excellent electrochemical performance.

FeVO4 nanobelts: controllable synthesis by electrospinning and visible-light photocatalytic properties

In the present work, one-dimensional FeVO4 nanobelts with the width of about 400u2009nm have been successfully prepared by a simple electrospinning process followed by the subsequent calcination process. The prepared products are characterized by thermogravimetric and differential scanning calorimetric, X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectra, scanning electron microscopy, UV-vis absorbance spectroscopy, nitrogen adsorption-desorption isotherms and total organic carbon. The results indicated that the as-prepared FeVO4 nanobelts belonging to the triclinic crystal system presented the one-dimensional belts structure. In addition, the morphologies, crystallite size and surface area of FeVO4 nanobelts were distinctly affected by the calcination temperature. And the FeVO4 nanobelts calcined at 600u2009°C for 2u2009h owned an excellent photocatalytic properties for the degradation of rhodamine B solution under the visible light irradiation.Graphical abstractSchematic representation of electrospinning process and morphology evolution of FeVO4 nanobelts during calcination process.

One-dimensional Bi 2 Mo x W 1-x O 6 sosoloids: controllable synthesis by electrospinning process and enhanced photocatalytic performance

One-dimensional Bi2MoxW1-xO6 (xxa0=xa00, 0.2, 0.5, 0.67, and 1) photocatalysts have been successfully synthesized for the first time by a straightforward electrospinning technique with a calcination process. The as-formed Bi2MoxW1-xO6 nanofibers are composed of inter-linked nanosheets of 30–50xa0nm in size and characterized by thermogravimetric and differential scanning calorimetric, Fourier transform infrared, Raman spectra, X-ray powder diffraction, scanning electron microscope, Brunauer-Emmett-Teller, transmission electron microscope, UV-Vis spectroscopy, photoluminescence, HPLC, and EIS. The photodegradation behaviors towards organic dyes, including rhodamine B (RhB) and methylene blue (MB) are investigated, and the results illustrate that Bi2Mo0.25W0.75O6 nanofibers exhibit the highest photocatalytic performance under visible light irradiation than Bi2MoxW1-xO6 (xxa0=xa00, 0.2, 0.5, 0.67, and 1) samples. The possible mechanisms of the enhanced photocatalytic properties are discussed in detail.

ZnO/γ-Bi 2 MoO 6 heterostructured nanotubes: electrospinning fabrication and highly enhanced photoelectrocatalytic properties under visible-light irradiation

ZnO/γ-Bi2MoO6 heterostructured nanotubes consisting of external shell of ZnO and γ-Bi2MoO6 with the outer diameter of about 400–500u2009nm and wall thickness of around 90u2009nm have been successfully fabricated by a combination of electrospinning and calcination strategy and characterized by TG-DSC, FT-IR, SEM, XRD, TEM, HRTEM, UV–Vis DRS, PL spectra, EIS, and TOC analysis. The photocatalytic activities of resulting nanotubes are evaluated through the photodegradation of methylene blue (MB) and measurements of photocurrent (PC) under visible-light irradiation. The results reveal that ZnO/γ-Bi2MoO6 nanotubes possess the exceptional photocatalytic and recycling properties. The enhanced degradation performance could be attributed to the positive synergistic effect of the well-established ZnO/γ-Bi2MoO6 hererostructures in promoting the transfer and separation of photogenerated carriers.Graphical abstractSchematic diagram of electron-hole separation mechanism for ZnO/γ-Bi2MoO6 nanotubes.

Facile synthesis and characterization of FeP x V 1 − x O 4 nanobelts with enhanced photocatalytic performance

AbstractWith doping a bit of phosphorus (P) into the lattice of FeVO4 nanobelts, FePxV1xa0−xa0xO4 solid solution nanobelts have been successfully synthesized for the first time via a simple electrospinning process. The as-prepared products were characterized by thermogravimetric and differential scanning calorimetry (TG-DSC), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis absorbance spectroscopy, and electrochemical impedance spectra (EIS). The results demonstrated that the lattice constants of FeVO4 were changed and transport of charge carriers was improved after doping P element. Furthermore, the FeP0.005V0.995O4 nanobelts presented an admirable one-dimensional morphology and the excellent photocatalytic properties for the degradation of methylene blue (MB) solution under the visible light irradiation.n Graphical abstractSchematic of electrospinning and calcination process and the crystal structure of FePxV1xa0−xa0xO4 nanobelts

Phosphorus-doped cerium vanadate nanorods with enhanced photocatalytic activity

CeVO4-based photocatalysts have been actively studied, but to the best of our knowledge, P-doped CeVO4 with enhanced photocatalytic activity has not been reported. Herein, novel P-doped CeVO4 nanorods were synthesized via a facile hydrothermal method. The doped P exists as PO4 tetrahedron which replaces VO4 tetrahedron. The crystal size, specific surface area, and light absorption ability of CeVO4 were tuned after doping CeVO4 by P. In particular, the separation and transmission efficiency of photogenerated electron-hole pairs were improved due to the internal electric field caused by the large charge density around PO4 tetrahedron. This conclusion was also confirmed by DFT calculations. The photocatalytic activities of different samples were tested via photodegradation of aqueous organic pollutants, and a feasible mechanism of photocatalytic reaction was proposed.

Synthesis of one-dimensional graphene-encapsulated TiO2 nanofibers with enhanced lithium storage capacity for lithium-ion batteries

The one-dimensional graphene/TiO2 composite nanofibers with the unique microstructures have been successfully synthesized via an efficient method and showed the improved rate capacity and excellent high rate performances as anode materials for lithium-ion batteries. The existence of graphene not only improves the electronic conductivity for serving as the additional transport channel but also avoids the agglomeration of anatase TiO2 nanofibers, consequently keeping their high active surface area. The graphene/TiO2 nanofibers possess the high reversible capacity (284.4xa0mAhxa0g−1 at a current density of 100xa0mAxa0g−1 after 100xa0cycles) and superior cyclic capacity retention at each of the different current rates for sequential cycles and exhibit the outstanding high rate performance with a capacity of 130xa0mAhxa0g−1 at a current rate as high as 3200xa0mAxa0g−1 after 300xa0cycles. The complementary and synergistic effect between anatase TiO2 nanofibers and graphene indicates that the graphene/TiO2 nanofibers could be one of the potential candidates for the related energy storage systems.