Wenbin Zhou

Characterization of zinc oxide crystal nanowires grown by thermal evaporation of ZnS powders

Abstract Semiconductor single-crystal ZnO nanowires have been successfully synthesized in bulk quantities by a simple and low cost process based on thermal evaporation of ZnS powders onto silicon substrates with the presence of Au catalyst. XRD of the product proves that the nanowires are the wurtzite structure of ZnO. Scanning electron microscopy and transmission electron microscopy show that the ZnO nanowires have diameters about 20–60 nm and lengths up to several tens of micrometers. The growth of ZnO nanowires is controlled by the conventional vapor–liquid–solid mechanism. The dependence of photoluminescence on temperatures was examined by He–Cd laser.

High-performance and compact-designed flexible thermoelectric modules enabled by a reticulate carbon nanotube architecture

It is a great challenge to substantially improve the practical performance of flexible thermoelectric modules due to the absence of air-stable n-type thermoelectric materials with high-power factor. Here an excellent flexible n-type thermoelectric film is developed, which can be conveniently and rapidly prepared based on the as-grown carbon nanotube continuous networks with high conductivity. The optimum n-type film exhibits ultrahigh power factor of ∼1,500 μW m−1 K−2 and outstanding stability in air without encapsulation. Inspired by the findings, we design and successfully fabricate the compact-configuration flexible TE modules, which own great advantages compared with the conventional π-type configuration modules and well integrate the superior thermoelectric properties of p-type and n-type carbon nanotube films resulting in a markedly high performance. Moreover, the research results are highly scalable and also open opportunities for the large-scale production of flexible thermoelectric modules.

Highly stretchable pseudocapacitors based on buckled reticulate hybrid electrodes

AbstractIn order to develop an excellent pseudocapacitor with both high specific capacitance and outstanding stretchability to match with other devices applicable in future wearable and bio-implantable systems, we focus our studies on three vital aspects: Stretchability of hybrid film electrodes, the interface between different components, and the integrated performance in stretchability and electrochemistry of supercapacitors based on single-walled carbon nanotube/polyaniline (SWCNT/PANI) composite films on pre-elongated elastomers. Owing to the moderate porosity, the buckled hybrid film avoids the cracking which occurs in conventional stretchable hybrid electrodes, and both a high specific capacitance of 435 F·g−1 and a high strain tolerance of 140% have been achieved. The good SWCNT/PANI interfacial coupling and the reinforced solid electrolyte penetration structure enable the integrated pseudocapacitors to have stretch-resistant interfaces between different units and maintain a high performance under a stretching of 120% elongation, even after 1,000 cyclic elongations.

A simple large-scale synthesis of coaxial nanocables: silicon carbide sheathed with silicon oxide

Abstract We reported a simple method to synthesize coaxial nanocables with silicon carbide core and amorphous silicon oxide sheath just by exposure of Au-coated silicon substrates to carbon monoxide at 1100 °C. The as-grown product was characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and micro-Raman spectroscopy. The obtained nanocables were in large scale, several tens of micrometers long, with the core a few nanometers to ten or more nanometers in diameter. The vapor–liquid–solid mechanism was proposed to elucidate the growth process.

Ultrahigh‐Power‐Factor Carbon Nanotubes and an Ingenious Strategy for Thermoelectric Performance Evaluation

An ingenious strategy is put forward to evaluate accurately the thermoelectric performance of carbon nanotube (CNT) thin films, including thermal conductivity, electrical conductivity, and Seebeck coefficient in the same direction. The results reveal that the as-prepared CNT interconnected films and CNT fibers possess enormous potential of thermoelectric applications because of their ultrahigh power factors.

Hydro-actuation of hybrid carbon nanotube yarn muscles

Hybrid hydro-responsive actuators are developed by infiltrating carbon nanotube yarns using poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate). These actuators demonstrate impressive rotation and contraction in response to water due to volumetric expansion of the helical arrangement of carbon nanotubes. The total torsional stroke is 3720 revolutions per m and the simultaneously generated contractive strain reaches 24% at a paddle-to-yarn mass ratio of 350. The contraction output can furthermore be significantly enhanced by constraining the rotational motion and it reaches 68% with an applied stress of 1 MPa. Additionally, hybrid yarns exhibit an approximately linear response to humidity changes and show extra capability of electrical actuation, which, combined with the excellent hydro-actuation performance, endow them with great potential for a variety of applications including artificial muscles, hydro-driven generators, moisture switches and microfluidic mixers.

Highly conductive and transparent carbon nanotube-based electrodes for ultrathin and stretchable organic solar cells*

In this work, we have presented a freestanding and flexible CNT-based film with sheet resistance of 60 Ω/ and transmittance of 82% treated by nitric acid and chloroauric acid in sequence. Based on modified CNT film as a transparent electrode, we have demonstrated an ultrathin, flexible organic solar cell (OSC) fabricated on 2.5-μm PET substrate. The efficiency of OSC, combined with a composite film of poly (3-hexylthiophene) (P3HT) and phenyl-C61 butyric acid methyl ester (PCBM) as an active layer and with a thin layer of methanol soluble biuret inserted between the photoactive layer and the cathode, can be up to 2.74% which is approximate to that of the reference solar cell fabricated with ITO-coated glass (2.93%). Incorporating the as-fabricated ITO-free OSC with pre-stretched elastomer, 50% compressive deformation can apply to the solar cells. The results show that the as-prepared CNT-based hybrid film with outstanding electrical and optical properties could serve as a promising transparent electrode for low cost, flexible and stretchable OSCs, which will broaden the applications of OSC and generate more solar power than it now does.