Honeycomblike network of vertically aligned AlN nanoplatelets was synthesized on etched Si substrate via a simple vapor phase method without catalyst. The nanoplatelets are hexagonal wurtzite AlN and their thickness is 10-100 nm. Field emission (FE) measurements showed that this nanostructure has a low turn-on field of 3.2-5.0 V/μm and a threshold field of 7.8-12.1 V/μm at sample-anode distances of 50-100 μm. The fluctuation of FE current with density of 10 mA/cm² over 5 h is lower than 3%. The low turn-on and threshold fields and the small fluctuation of current demonstrate that this two-dimensional AlN nanostructure is a promising FE material.

Y. B. Tang;H. T. Cong;会明 成

Applied Physics Letters

2006

With the assistance of a ferroelectric field in PbTiO₃ nanoplates, noble metals and metal oxides can be selectively deposited on the positively and negatively charged (001) facets of the nanoplates. Compared to PbTiO₃ with randomly deposited reducing co-catalyst Pt particles, photocatalytic H₂ evolution on PbTiO₃ with Pt particles selectively deposited on the positively charged (001) facet is an order of magnitude better.

Chao Zhen;Jimmy C. Yu;Gang J. Liu;会明 成

Chemical Communications

2014-8-12

The strong band-to-band absorption of photocatalysts spanning the whole visible-light region (400–700 nm) is critically important for solar-driven photocatalysis. Although it has been actively and widely used as a photocatalyst for various reactions in the past four decades, TiO₂ has a very poor ability to capture the whole spectrum of visible light. In this work, by controlling the spatially homogeneous distribution of boron and nitrogen heteroatoms in anatase TiO₂ microspheres with a predominance of high-energy {001} facets, a strong visible-light absorption spectrum with a sharp edge beyond 680 nm has been achieved. The red TiO₂ obtained with homogeneous doping of boron and nitrogen shows no increase in defects like Ti³⁺ that are commonly observed in doped TiO₂. More importantly, it has the ability to induce photocatalytic water oxidation to produce oxygen under the irradiation of visible light beyond 550 nm and also the photocatalytic reduction of water to produce hydrogen under visible light. These results demonstrate the great promise of using red TiO₂ for visible-light photocatalytic water splitting and also reveal an attractive strategy for realizing the wide-spectrum visible-light absorption of wide-band-gap oxide photocatalysts.

Xingxing Hong;Jun Tan;Huaze Zhu;Ningdong Feng;Yongqiang Yang;John T.S. Irvine;Lianzhou Wang;Gang Liu;会明 成

Chemistry - A European Journal

2019-2-1

In this paper, carbon nanotubes (CNTs) were added into poly(vinyl alcohol) (PVA) hydrogels to modify their mechanical properties. A series of CNT/PVA hybrid hydrogels were prepared by freezing/thawing method. The mechanical and swelling properties of all hybrid hydrogels are better than those of the original PVA hydrogel. Especially, for CNTP-0.5 specimen with 0.5% w/w CNTs, its tensile modulus, tensile strength and strain at break are increased by 78.2%, 94.3% and 12.7%, respectively. And its swelling behavior is different from that of the pure PVA hydrogel. Its final swelling ratios at room temperature and 310 K are increased by 35.7% and 44.9%, respectively.

Xin Tong;Jingjing Zheng;Yancheng Lu;Zhenfang Zhang;会明 成

Materials Letters

2007-4

Vacancy defects can play an important role in modifying the electronic structure and the properties of photoexcited charge carriers and consequently the photocatalytic activity of semiconductor photocatalysts. By controlling the polycondensation temperature of a dicyandiamide precursor in the preparation of graphitic carbon nitride (g-C ₃N ₄), we introduced nitrogen vacancies in the framework of g-C ₃N ₄. These vacancies exert remarkable effects on modifying the electronic structure of g-C ₃N ₄ as shown in UV-visible absorption spectra and valence band spectra. Steady and time-resolved fluorescence emission spectra show that, due to the existence of abundant nitrogen vacancies, the intrinsic radiative recombination of electrons and holes in g-C ₃N ₄ is greatly restrained, and the population of short-lived and long-lived charge carriers is decreased and increased, respectively. As a consequence, the overall photocatalytic activity of the g-C ₃N ₄, characterized by the ability to generate •OH radicals, photodecomposition of Rhodamine B, and photocatalytic hydrogen evolution under both UV-visible and visible light, was remarkably improved.

Ping Niu;Gang Liu;会明 成

Journal of Physical Chemistry C

2012-5-24

A simple, fast and cost-effective method for monolithic carbon aerogels (CAs) preparation was proposed through sol-gel polycondensation of resorcinol with formaldehyde in a basic aqueous solution followed by ambient pressure drying without solvent exchange, and carbonization. The microstructure and network strength of CAs were tailored by adjusting the catalyst concentration ([resorcinol]/[sodium carbonate] in the range of 300–2000), water content ([deionized water]/[resorcinol] equals to 17 and 24, respectively), and gelation temperature (T_gel in the range of 30−90 °C). Resultantly, the CAs with a wide range of density (0.30–1.13 g/cm³), high specific surface area (465−616 m²/g), high compressive strength (6.5–147.4 MPa) and low thermal conductivity (0.065-0.120 W·m⁻¹ K⁻¹) were obtained in this work. Moreover, the large-sized CAs (100 × 100 × 20 mm³) can also be prepared by this method since the formed robust skeleton network can resist shrinkage/collapse of pore structure and prevent cracking during drying. The improved mechanical strength and monolithic forming abilities could be mainly attributed to the uniform arrangement of carbon particles and pores, fine particle size, abundant network structure and enhanced particle neck.

Zhi Yang;Jian Li;Xiaojing Xu;Shengyang Pang;Chenglong Hu;Penglei Guo;Sufang Tang;会明 成

Journal of Materials Science and Technology

2020-8-1

The selectivity of the CO₂ photoreduction reaction in the presence of water vapour can be modulated by the band structure of a g-C₃N₄ photocatalyst. The major products obtained using bulk g-C₃N₄ with a bandgap of 2.77 eV and g-C₃N₄ nanosheets with a bandgap of 2.97 eV are acetaldehyde (CH₃CHO) and methane (CH₄), respectively.

Ping Niu;Yongqiang Yang;Jimmy C. Yu;Gang Liu;会明 成

Chemical Communications

2014-8-18

Massive macroscopic ropes of well-aligned single-walled carbon nanotubes (SWNTs) with a larger mean diameter of about 1.72 nm, synthesized by a semicontinuous hydrogen arc discharge method, were employed for electrochemical hydrogen adsorption experiments. A high discharge capacity of 503 mAh/g, corresponding to 1.84 wt % hydrogen, was achieved reproducibly at 25°C under normal atmosphere for about 200 mg SWNT sample. This result implies that the SWNTs are highly promising electrochemical hydrogen storage materials for rechargeable batteries.

Gui Ping Dai;Chang Liu;Min Liu;Mao Zhang Wang;会明 成

Nano Letters

2002-5

Amorphous carbon nitride (ACN) with a bandgap of 1.90 eV shows an order of magnitude higher photocatalytic activity in hydrogen evolution under visible light than partially crystalline graphitic carbon nitride with a bandgap of 2.82 eV. ACN is photocatalytically active under visible light at a wavelength beyond 600 nm.

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

Advanced Materials

2015-8-1

The study of the thermal expansion of a composite of single-walled carbon nanotubes and nanocrystalline aluminium was presented. Coarse-grained Al and single crystal silicon (Si) samples of the same size were used to compare the coefficient of thermal expansion (CTE) of the composites with conventional Al and semiconductor materials. It was observed that the measured CTE values of the SWNTs/nano-Al composites were significantly lower than those predicted by ROM, Kerner's and Schapery's model. It was also observed that the CTEs of the composites decreased with an increase in the fraction of the SWNTs, and the CTE of the 15 vol% SWNT/nano-Al composite was about one third of that of nano-Al.

Yongbing Tang;Hongtao Cong;Rong Zhong;会明 成

Carbon

2004