Tongyi Guo

Cheap, Gram-Scale Fabrication of BN Nanosheets via Substitution Reaction of Graphite Powders and Their Use for Mechanical Reinforcement of Polymers

As one of the most important two-dimensional (2D) materials, BN nanosheets attracted intensive interest in the past decade. Although there are many methods suitable for the preparation of BN sheets, finding a cheap and nontoxic way for their mass and high-quality production is still a challenge. Here we provide a highly effective and cheap way to synthesize gram-scale-level well-structured BN nanosheets from many common graphite products as source materials. Single-crystalline multi-layered BN sheets have a mean lateral size of several hundred nanometers and a thickness ranging from 5 nm to 40 nm. Cathodoluminescence (CL) analysis shows that the structures exhibit a near band-edge emission and a broad emission band from 300 nm to 500 nm. Utilization of nanosheets for the reinforcement of polymers revealed that the Youngs modulus of BN/PMMA composite had increased to 1.56 GPa when the BNs fraction was only 2 wt.%, thus demonstrating a 20% gain compared to a blank PMMA film. It suggests that the BN nanosheet is an ideal mechanical reinforcing material for polymers. In addition, this easy and nontoxic substitution method may provide a universal route towards high yields of other 2D materials.

Investigation on the photoconductive behaviors of an individual AlN nanowire under different excited lights

Ultra-long AlN nanowire arrays are prepared by chemical vapor deposition, and the photoconductive performances of individual nanowires are investigated in our self-built measurement system. Individual ultra-long AlN nanowire (UAN) exhibits a clear photoconductive effect under different excited lights. We attribute the positive photocurrent response of individual UAN to the dominant molecular sensitization effect. It is found that they have a much faster response speed (a rise and decay time of about 1 ms), higher photocurrent response (2.7×106), and more reproductive working performance (the photocurrent fluctuation is lower than 2%) in the air environment. Their better photoconductive performances are comparable to many nanostructures, which are suggested to be a candidate for building promising photosensitive nanodevices in the future.

A simple SVS method for obtaining large-scale WO3 nanowire cold cathode emitters at atmospheric pressure and low temperature

Large-scale WO3 nanowire patterns have been successfully fabricated on a 3.5 inch glass substrate at atmospheric pressure by a simple no-catalyst method. The nanowires were observed to have a mean length of about 40 μm, and their aspect ratio reaches 200. The nanowires were proven to be single crystalline WO3 with a monoclinic structure. It is found that the growth region and growth density of the WO3 nanowires differ with the interval or the width of the W stripes. By combination of designing a series of experiments and analyzing the growth kinetics theory, a novel self-supported vapor–solid (SVS) mechanism is proposed to be responsible for the formation of WO3 nanowires. Field emission (FE) measurements show that the WO3 nanowire patterns have excellent FE performance, which have a low turn-on field of 2.9 V μm−1 and good field emission uniformity of over 85%. Moreover, this SVS method may provide a helpful reference on low-temperature and no-catalyst growth of other metal oxide nanostructure arrays at atmospheric pressure.

Growth and field emission performance of micro-patterned boron nanowire arrays

Boron nanowire micro-patterns are prepared by CVD method. Ni film is chosen to be the catalyst for fabrication of boron nanowires. Patterned boron nanowires are found to have relatively lower turn-on field and good emission uniformity, which should have a promising future in FED area.

Synthesis of WO 2 nanowire arrays on glass substrate for field emission application

WO2 nanowires were grown on Cr/Al electrode on a 0.5 inch glass substrate at low temperature. Field emission properties were measured to investigate their future application in a field emission display devices. The WO2 nanowires are found to have a turn-on field of 9.8 MV/m and their emission current density can reach 1.6 mA/cm2 when the applied field is 14 MV/m. It suggests that they should have a promising future in field emission applications if their emission uniformity can be further improved.

Study of the working performance of WO 2 nanowire arrays in gated field emission display devices

Tungsten oxide nanowires are integrated into gated wing-type field emission display (FED) devices, which are synthesized at low temperature of 550 °C by catalyzed-growth CVD way. The emission behaviors of the device are testified by transparent anode way to investigate their future application. These WO2 FED devices are found to have a turn-on field of 5.76 V/μm and their emission current density reaches 0.59 mA/cm2 when the applied field is 7.55 V/μm. It suggests that they should have a promising future in field emission applications if their emission uniformity can be further improved.