Chuanyin Xiong

A three-dimensional MnO2/graphene hybrid as a binder-free supercapacitor electrode

Highly aligned manganese dioxide (MnO2) nanowall arrays electrodeposited onto Ti sheets are used as substrates to grow graphene (GR) through chemical vapor deposition (CVD), thus forming a three-dimensional (3D) MnO2/GR hybrid composite. Furthermore, a 3D MnO2/GR hybrid with different structures and properties has been prepared at different temperatures. The as-prepared hybrid materials could be directly used as supercapacitor electrodes without any binder and conductive additive, and fully maintain the high conductivity and high specific area of GR, and large pseudocapacitance of MnO2 nanowall arrays. In aqueous electrolytes, the hybrids show a high specific capacitance of ∼326.33 F g−1 with good cycling stability at the scan rate of 200 mV s−1 and high energy density of 23.68 W h kg−1 while maintaining high power density of 7270 W kg−1. The preparation method provides a novel method to fabricate 3D graphene-based composite materials, and the as obtained hybrid electrode demonstrates its potential applications in supercapacitors.

Three-Dimensional Graphene/MnO2 Nanowalls Hybrid for High-Efficiency Electrochemical Supercapacitors

In this paper, a facile method is designed to fabricate three-dimensional (3D) graphene (GR)/manganese dioxide (MnO2) nanowall electrode material. The 3D GR/MnO2 hybrid is prepared by a combination...

A three-dimensional vertically aligned carbon nanotube/polyaniline composite as a supercapacitor electrode

Highly vertically aligned carbon nanotube arrays grown on the surface of pure titanium plates by chemical vapor deposition serve as substrates for electrodepositing polyaniline, thus fabricating three-dimensional carbon nanotube/polyaniline composites. In addition, X-ray diffraction and Raman spectroscopy are applied to investigate the structures of the as-prepared hybrids. Morphological analysis of the nanotube/polyaniline composites is performed by high resolution SEM and transmission electron microscopy. The combination of the three-dimensional carbon nanotube architecture and conducting polyaniline surprisingly generates a synergistic effect on electrochemical performance which is particularly important. Consequently, the vertically aligned carbon nanotube/polyaniline hybrids exhibit excellent characteristics in terms of specific capacitance (752.5 F g−1) and power density (5364 W kg−1) at a scanning rate of 100 mV s−1. Furthermore, the capacity retention can reach over 82% (after 10 000 cycles). This work highlights the critical role of the introduction of vertically laid carbon nanotubes with highly conducting polyaniline in improving the performance of supercapacitors.

Preparation and electromagnetic wave absorbing properties of 3D graphene/pine needle-like iron nano-acicular whisker composites

The improvement of high reflection loss and broad frequency bandwidth for electromagnetic wave absorption materials is a long-term effort. The superb micro-structures of the absorber have significant impact on increasing reflection loss and broadening frequency bandwidth. Herein, we prepared 3D graphene by chemical vapor deposition and then 3D graphene/pine needle-like iron nano-acicular whisker composites were in situ synthesized by an electrochemical deposition process under an electric field using 3D graphene as substrate. The nano-acicular whiskers show different sizes and the mean diameter of the individual iron nano-acicular whiskers was about 150 nm. The saturation magnetization (MS) of the 3D graphene/iron nano-acicular whisker composite was about 42.65 emu g−1 and the coercivity (Hc) was 143 Oe, and it shows good magnetic properties. In the frequency range of 2–18 GHz, the reflection loss value of the graphene/iron nano-acicular whisker composites with a thickness of 2 mm could reach −12.81 dB at 10.95 GHz and the effective absorption bandwidth below −10 dB was 2.16 GHz. The nano-acicular whiskers could effectively improve the electromagnetic wave absorbing properties. The results suggested that the as-prepared graphene/iron nano-acicular whisker nanocomposite showed great potential applications as a new absorber material.

In situ synthesis and electromagnetic wave absorbing properties of sandwich microstructured graphene/La-doped barium ferrite nanocomposite

The development of high reflection loss and broad frequency bandwidth for electromagnetic wave absorbing materials has been pursued for a long time. Constructing a rational microstructure of an absorber will have significant impact on reflection loss increase and frequency bandwidth broadening. Herein, we successfully prepare a sandwich microstructured graphene/BaFe12O19 nanocomposite by an in situ auto-combustion method. Compared to pure BaFe12O19, the sandwich microstructured graphene/BaFe12O19 showed better electromagnetic wave absorbing properties. Furthermore, the sandwich microstructured graphene/Ba0.8La0.2Fe12O19 nanocomposite was prepared with La-doped BaFe12O19 using the same method. The obtained graphene/Ba0.8La0.2Fe12O19 nanocomposite exhibited a saturation magnetization of 26.55 emu g−1 at room temperature and exhibited excellent magnetic performance. The maximum reflection loss of the sandwich microstructured graphene/Ba0.8La0.2Fe12O19 nanocomposite with a thickness of 1 mm could reach up to −40.26 dB, and a frequency bandwidth value below −10 dB was observed up to 3.87 GHz within the frequency range of 2–18 GHz.