Peining Zhu

Facile Fabrication of TiO2–Graphene Composite with Enhanced Photovoltaic and Photocatalytic Properties by Electrospinning

We report the fabrication of one-dimensional TiO(2)-graphene nanocomposite by a facile and one-step method of electrospinning. The unique nanostructured composite showed a significant enhancement in the photovoltaic and photocatalytic properties in comparison to TiO(2) as demonstrated in dye-sensitized solar cells and photodegradation of methyl orange.

Long term cycling studies of electrospun TiO2 nanostructures and their composites with MWCNTs for rechargeable Li-ion batteries

Nanofiber- and rice grain-shaped TiO2 nanostructures and their composites with functionalized multiwalled carbon nanotubes were fabricated by electrospinning and subsequent sintering process for applications in Lithium ion batteries. The fabricated nanostructures were characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, scanning-and transmission electron microscopy and surface area measurements. All nanostructured materials showed average discharge-charge plateaux of 1.75 to 1.95V. The nanofibrous- and rice grain-shaped TiO2 nanomaterials showed stable performances of 136 (± 3) mAh g−1 and 140 (± 3) mAh g−1, respectively, at the end of 800 cycles in the cycling range of 1.0–2.8 V vs.Li at a current rate of 150 mA g−1. TiO2–CNT (4 wt.%) composites showed a slightly lower capacity value but better capacity retention (8% capacity loss between 10–800 cycles). We believe that the present long term cycling materials would have wide interests in lithium ion batteries research.

Controlled Synthesis of BiOCl Hierarchical Self-Assemblies with Highly Efficient Photocatalytic Properties

Herein, we report the controlled synthesis of bismuth oxychloride (BiOCl) hierarchical self-assemblies under hydrothermal conditions and demonstrate their high photocatalytic properties. An interesting morphological evolution from microplates to nanoplate assemblies with microsphere-, microdisk-, and microflower-like structures is investigated by adjusting the amounts of surfactant poly(vinyl pyrrolidone) (PVP). It has been found that three types of three-dimensional (3D) BiOCl micromaterials are formed layer-by-layer from a large number of interconnected 2D nanoplates with a mean side length of about 20 nm. A possible crystal growth and formation mechanism is proposed as a plausible mechanistic interpretation for the self-assembly of nanoplates into the observed microstructures that is based on the detailed experiments. Furthermore, the photocatalytic properties of the obtained samples are investigated by the photodegradation analysis of Rhodamine B and methylene orange (RhB and MO) dyes, thus indicating that the microspherelike BiOCl hierarchical structure has a higher photocatalytic activity than the microdisk-like and microflower-like BiOCl structures, owing to its novel structure with a high surface area. Introduction

Monodispersed Ag nanoparticles loaded on the PVP-assisted synthetic Bi2O2CO3 microspheres with enhanced photocatalytic and supercapacitive performances

Uniform 1 μm-sized Bi2O2CO3 microspheres constructed by nanoplates with a thickness of about 12 nm have been obtained through a facile hydrothermal method. Ag is deposited on the surface of Bi2O2CO3via a subsequent facile photoreduction process. In the synthesis process, polyvinylpyrrolidone (PVP) is used as a reactant that not only provides C and O sources but also serves as a template to induce the nanoplate-assembly to form microspheres. With the addition of KCl in the synthesis, the size of the Bi2O2CO3 microspheres can be reduced from ∼6 μm to ∼1 μm. It is demonstrated that PVP and KCl play key roles in the formation of such hierarchical microspheres. The obtained Bi2O2CO3 and novel Ag/Bi2O2CO3 composites are evaluated for photocatalytic and supercapacitive applications. The test result of the photocatalytic activity demonstrates that 0.6 wt% loading of Ag on the Bi2O2CO3 microspheres exhibits significantly enhanced activity for the photodegradation of methyl orange (MO) dye, compared with Bi2O2CO3. The enhanced photocatalytic activity can be attributed to the Ag deposits acting as electron traps and the high surface area of Bi2O2CO3. Furthermore, the Ag/Bi2O2CO3 composites are primarily evaluated as supercapacitor electrodes, which deliver specific capacities of 620 and 361 F g−1 at current densities of 1 and 5 A g−1, respectively.

Maghemite Nanoparticles on Electrospun CNFs Template as Prospective Lithium-Ion Battery Anode

In this work, maghemite (γ-Fe2O3) nanoparticles were uniformly coated on carbon nanofibers (CNFs) by a hybrid synthesis procedure combining an electrospinning technique and hydrothermal method. Polyacrylonitrile nanofibers fabricated by the electrospinning technique serve as a robust support for iron oxide precursors during the hydrothermal process and successfully limit the aggregation of nanoparticles at the following carbonization step. The best materials were optimized under a carbonization condition of 600 °C for 12 h. X-ray diffraction and electron microscopy studies confirm the formation of a maghemite structure standing on the surface of CNFs. The average size of γ-Fe2O3 nanoparticles is below 100 nm, whereas CNFs are ∼150 nm in diameter. In comparison with aggregated bare iron oxide nanoparticles, the as-prepared carbon-maghemite nanofibers exhibit a higher surface area and greatly improved electrochemical performance (>830 mAh g(-1) at 50 mA g(-1) for 40 cycles and high rate capacity up to 5 A g(-1) in the voltage range of 0.005-3 V vs Li). The greatly enhanced electrochemical performance is attributed to the unique one-dimensional nanostructure and the limited aggregation of nanoparticles.

Which is a superior material for scattering layer in dye-sensitized solar cells—electrospun rice grain- or nanofiber-shaped TiO2?

A thin film of rice grain- and nanofiber-shaped titanium dioxide (TiO2) nanostructures was fabricated as an effective scattering layer on the nanoparticle electrodes in dye-sensitized solar cells by electrospinning. The rice grain-like nanostructures are found to be superior to the nanofibers in scattering light with a 15.7% enhancement in efficiency compared to 9.63% for nanofibers.

Highly improved rechargeable stability for lithium/silver vanadium oxide battery induced via electrospinning technique

The electrospinning technique and the hydrothermal method are two well-known ways to fabricate nanostructures effectively for battery applications. Herein we report a novel preparation of β-Ag0.33V2O5 nanostructures via an electrospinning technique followed by a hydrothermal process. These electrospun-derived materials are composed of single crystalline nanorods with self-limited aggregation verified by XRD, SEM and TEM results. Characterized by electroanalytical techniques, β-Ag0.33V2O5 nanostructures show an initial high capacity ∼250 mA h g−1 and improved cycling stability with a capacity loss of only ∼1 mA h g−1 per cycle after 30 runs at a current of 20 mA g−1. The materials exhibit a moderate capacity drop at higher charge/discharge rates. Not only is this among the best cycling performance reported so far for the silver vanadium oxide (SVO) series, but the novel atomic inter-planar construction and unique nano-morphology demonstrate a promising road to enhance the cycling stability for electrode materials using the electrospinning technique.

Electrospun conductive polyaniline–polylactic acid composite nanofibers as counter electrodes for rigid and flexible dye-sensitized solar cells

Conductive polyaniline doped with 10-camphorsulfonic acid (PANI·CSA) blended with polylactic acid (PLA) composite films are directly deposited on rigid fluorine-doped tin oxide and flexible indium tin oxide-coated polyethylene naphthalate substrates by using a simple electrospinning method. The scanning electron microscope and atomic force microscope images show that the PANI·CSA–PLA film is assembled from about 200 nm-diameter nanofibers, with a generally uniform thickness of about 2 μm. The three-dimensional porous fibrous PANI·CSA–PLA films indicate good electrocatalytic performance for I3−/I− electrolyte, demonstrated by electrochemical impedance spectra and cyclic voltammetry measurements. The photoelectric conversion efficiency of the dye-sensitized solar cells (DSCs) firstly based on such rigid and flexible PANI·CSA–PLA counter electrodes achieves 5.3% and 3.1% under 1 sun illumination of 100 mW cm−2 (AM 1.5), respectively, which is close to that of sputtered Pt-based DSCs. In addition, the rigid PANI·CSA–PLA-based DSC demonstrates good stability. As the PANI·CSA–PLA counter electrodes can be obtained in a short time at room temperature, they are potentially applicable in large-area DSCs and suitable for flexible DSCs.

Controlled synthesis and photoelectric application of ZnIn2S4 nanosheet/TiO2 nanoparticle composite films

This paper reports the controlled synthesis of ZnIn2S4 nanosheet/screen-printed TiO2 nanoparticle composite films by a facile hydrothermal method and demonstrates the photoelectric application of ZnIn2S4 nanosheets as potential inorganic sensitizers in semiconductor-sensitized solar cells. The ZnIn2S4 nanosheets with a thickness of about 20 nm and a lateral size of 2 μm were distributed not only on the surface but also in the interior of the TiO2 nanoparticles, indicating a full contact between ZnIn2S4 nanosheets and TiO2 nanoparticles. The ZnIn2S4/TiO2 composite films demonstrated bandgap energy values ranging from 2.38–2.64 eV and their peaks can shift from the ultraviolet region to the visible region, compared with that of the TiO2/FTO film (FTO: fluorine-doped tin oxide). The densities, thicknesses, morphologies of the ZnIn2S4 nanosheets could be controlled by adjusting the experimental parameters, including reaction times, temperatures and concentrations. The possible formation mechanism and growth process of the ZnIn2S4 nanosheets on the TiO2 nanoparticles were discussed based on the experimental results. Furthermore, as a proof-of-concept, ZnIn2S4/TiO2-based inorganic semiconductor-sensitized solar cells were fabricated by filling polysulfide liquid electrolyte into the electrodes and the device exhibited a reproducible photovoltaic response.

TiO2 Derived by Titanate Route from Electrospun Nanostructures for High-Performance Dye-Sensitized Solar Cells

We report the use of highly porous, dense, and anisotropic TiO(2) derived from electrospun TiO(2)-SiO(2) nanostructures through titanate route in dye-sensitized solar cells. The titanate-derived TiO(2) of high surface areas exhibited superior photovoltaic parameters (efficiency > 7%) in comparison to the respective electrospun TiO(2) nanomaterials and commercially available P-25.