Boron-sputtered highly oriented pyrolytic graphite (HOPG) was prepared through laser sputtering. The superperiodic features of the HOPG surface were imaged using scanning tunneling microscopy (STM). Superperiodic hexagonal features were observed after oxidation at 580°C for 30 minutes. The observed superperiodic lattice was explained by a Moire pattern with a rotation angle of 6.5°.

D. P. Dai;T. S. Xie;会明 成;Y. Zhao;H. Q. Ye

Carbon

1999

Potassium ion batteries (PIBs) have shown great potential as a next-generation electrochemical energy storage system, due to the natural abundance of potassium and the relatively low redox potential of K ions. To accommodate the large ionic radius of K ions, conversion-type electrode materials are regarded as suitable candidates for K ion storage. However, the triggering mechanism of a conversion reaction in most anode materials of PIBs is unclear, which limits their further development. To reveal the mechanism, in this work, MoSe₂, MoS₂, and MoO₂ were selected as model materials, guided by theoretical calculations, to investigate the K ion storage process. Through ex situ characterization, it was found that intercalation reactions preferentially occur in MoSe₂ and MoS₂, while an adsorption reaction preferentially occurs in MoO₂. This is because of the larger interlayer spacing and lower K ion intercalation barrier in MoSe₂ and MoS₂ than in MoO₂. The preferential intercalation reactions are able to induce a further conversion reaction by reducing the reaction barrier, thereby realizing high K ion storage capacities. As a result, the MoSe₂−rGO and MoS₂−rGO hybrids showed higher reversible capacities than the MoO₂−rGO hybrid. By demonstrating a relationship between intercalation and the conversion reaction and understanding the mechanism, guidance is provided for selecting the electrode materials to obtain PIBs with high performance.

Jinzhi Sheng;Tianshuai Wang;Junyang Tan;Wei Lv;Ling Qiu;Qianfan Zhang;Guangmin Zhou;会明 成

ACS Nano

2020-10-27

The effect of the dopant anion on thermodynamic tailoring in TiF₃- and TiCl₃-doped Na₃AlH₆ was investigated by pressure-composition desorption isotherm measurements. It was found that the dissociation pressure of the TiF₃-doped hydride was substantially higher than that of the TiCl₃-doped sample. This finding agrees well with the theoretically demonstrated thermodynamic modification arising upon F^- substitution in the hydride lattice, thus providing direct experimental evidence to support functionality of F^- anion.

Xiang Dong Kang;Ping Wang;会明 成

Scripta Materialia

2007-3

A joint chemical vapor infiltration-precursor infiltration and pyrolysis (CVI-PIP) process was used to fabricate C/C-SiC-ZrC composites with different volume ratio of CVI-derived C-SiC. The composite with a C-SiC volume ratio of 0.91 has a higher tensile and flexural strength of 181.7 MPa and 352.8 MPa, respectively, and also exhibits a better anti-oxidation property at 800∼1400 °C for 30 h. After an oxyacetylene ablation for 600 s at ∼2100 °C, the composite with a C-SiC volume ratio of 0.12 possesses a better anti-ablation performance with a linear and mass ablation rates of 0.94 um × s⁻¹ and 0.13 mg × cm^-2×s⁻¹, respectively.

Jinjin Yao;Shengyang Pang;Chenglong Hu;Jian Li;Sufang Tang;会明 成

Corrosion Science

2020-1

Two remarkable features were created by selectively breaking hydrogen bonds existing in the C-N covalent bonds-dominated intralayer framework of layered carbon nitride. One is the increased band tails or localized states close to the band edges as a result of the destruction of intralayer long-range atomic order and loss of partial nitrogen atoms. The other is the abundant pores formed throughout the whole particles as a result of volume shrinkage with the breaking of hydrogen bonds. These abundant pores subsequently promote the transfer of electrons to reach the lateral surface of the pores by providing additional reductive reaction sites. As a consequence of these favorable changes in improving all three basic processes of photocatalysis, the carbon nitride with an optimized breaking of hydrogen bonds gives a significantly enhanced photocatalytic hydrogen generation activity under visible light. These results suggest that the number of the reductive reaction sites of the carbon nitride with broken hydrogen bonds is greatly increased with the abundant lateral edges/surfaces of the pore walls as additional reductive reaction sites.

Yuyang Kang;Yongqiang Yang;Li Chang Yin;Xiangdong Kang;Lianzhou Wang;Gang Liu;会明 成

Advanced Materials

2016

Huan Quan Sun;Guo Sun;会明 成;Su Ying Wu

Shiyou Kantan Yu Kaifa/Petroleum Exploration and Development

2002-6

Unidirectional carbon fibre reinforced SiC composites were prepared from four types of carbon fibres, PAN-based HSCF, pitch-based HMCF, CF50 and CF70, through nine cycles or twelve cycles of impregnation of polycarbosilane and subsequent pyrolysis at 1200°C. The polycarbosilane-derived matrix was found to be β-SiC with a crystallite size of 1.95 nm. The mechanical properties of the composites were evaluated by four-point bending tests. The fracture behavior of each composite was investigated based on load-displacement curves and scanning electron microscope (SEM) observation of fracture surfaces of the specimens after tests. It was found that CF50/SiC and CF70/SiC exhibited high strength and non-brittle fracture mode with multiple matrix cracking and extensive fibre pullout, whereas HSCF/SiC and HMCF/SiC exhibited low strength and brittle fracture mode with almost no fibre pullout. The differences in the fracture modes of these carbon fibre/SiC composites were thought to be due to differences in interfacial bonding between carbon fibres and matrix. Values of flexural strengths of CF70/SiC and CF50/SiC were 967 MPa and 624 MPa, respectively, which were approximately 75% and 38% of the predicted values. The relatively lower strength of CF50/SiC, compared with CF70/SiC, was mainly attributed to the shear failure of CF50/SiC during bending tests.

G. B. Zheng;H. Sano;Y. Uchiyama;K. Kobayashi;会明 成

Journal of Materials Science

1999

Recent research on the development of flexible lithium-ion batteries (LIBs) has achieved unprecedented progress. The realization of flexibility of LIBs often comes with a compromise of other features, which is unfavorable for their practical application. In this perspective, we briefly review how the design of flexible LIBs has been achieved, and then use textile LIBs as an example of how the flexibility affects their performance. We also detail future challenges and opportunities in design and fabrication of flexible LIBs for practical applications.

Linchao Zeng;Ling Qiu;会明 成

Energy Storage Materials

2019-12

Multiwalled carbon nanotube (MWNT)-filled high-density polyethylene (HDPE) composites were prepared by a solution-precipitation process, and the temperature dependence of electrical conductivity of the MWNT/HDPE composites was studied. An obvious positive temperature coefficient (PTC) effect was found in the MWNT/HDPE composites with a relatively low MWNT concentration. Compared with that of carbon black (CB)/HDPE composite, the negative temperature coefficient (NTC) effect of the MWNT/HDPE composite at temperature above the melting temperature of HDPE was much less obvious and could be further eliminated after 80 kGy γ -ray irradiation. The mechanism of the PTC and NTC effects in MWNT/HDPE composites was discussed.

X. J. He;J. H. Du;Z. Ying;会明 成;X. J. He

Applied Physics Letters

2005-2-7

Mg-40%AB2 nano/amorphous composite was produced by ball-milling. The kinetics, cycling properties and the resistance to oxidation were examined. This composite possesses high hydrogen storage capacity (4. 4%) and excellent kinetic properties, even at moderate temperature. XRD, SEM, EDS and TEM were used to characterize the composite before and after hydriding. The nanometer size amorphous Zr0.9Tio.i(Nio.57Mn0.28Vo.iCoo.o5)M particles, distributing uniformly on the surface and in the bulk of Mg particles, and a significant amount of phase boundary, imperfections introduced by ball-milling contribute to the enhanced hydrogen absorption/desorption rate.

Leng Haiyan;Chen Demin;Chen Lian;会明 成;Yang Ke

Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering

2001