Peng Lv

Schottky solar cells based on graphene nanoribbon/multiple silicon nanowires junctions

We report the construction of Schottky solar cells based on graphene nanoribbon/multiple silicon nanowires (SiNWs) junctions. Only a few (∼10) SiNWs were involved to miniaturize the solar cell for nanoscale power source applications. It was found that doping level of the SiNWs played an important role in determining the device performance. By increasing the doping level, solar cell with open circuit voltage of 0.59 V and energy conversion efficiency of 1.47% were achieved under AM 1.5G illumination. The large effective junction area of the radial Schottky junction was responsible for the high device performance.We report the construction of Schottky solar cells based on graphene nanoribbon/multiple silicon nanowires (SiNWs) junctions. Only a few (∼10) SiNWs were involved to miniaturize the solar cell for nanoscale power source applications. It was found that doping level of the SiNWs played an important role in determining the device performance. By increasing the doping level, solar cell with open circuit voltage of 0.59 V and energy conversion efficiency of 1.47% were achieved under AM 1.5G illumination. The large effective junction area of the radial Schottky junction was responsible for the high device performance.

Enhanced Reversible Photoswitching of Azobenzene-Functionalized Graphene Oxide Hybrids

An enhanced photoinduced reversible switching of graphene oxide-azobenzene (GO-AZO) hybrid was investigated as a highly sensitive photoswitch. The internal short-range ordered crystalline structure of GO-AZO hybrid was advantageous to charge transfer. The AZO moieties on GO underwent a rapid trans-cis photoisomerization upon ultraviolet irradiation due to the electron interaction between AZO and GO. The GO-AZO hybrid film showed an enhanced reversible photoswitching performance with high on/off ratio of 8 and fast response time less than 500 ms. The high sensitivity of GO-AZO switch arises from the intramolecular donor-acceptor architecture with efficient charge transfer.

Super-elastic graphene/carbon nanotube aerogels and their application as a strain-gauge sensor

A synergistic assembly strategy was developed to fabricate super-elastic all-carbon aerogels by integrating carbon nanotubes (CNTs) into three-dimensional graphene. The CNTs in the aerogels prevented the sliding between the graphene sheets and enhanced the stiffness of cell walls, which provided the aerogels with super-elasticity. Mechanical tests showed that the graphene/CNT aerogels could fully recover without fracture even after 90% compression. The potential application of the sensing compressive strain for the aerogels was also demonstrated. The electrical resistance response of the aerogels was highly constant to the multiple cycles of compression. The strain-gauge sensitivity of graphene/CNT aerogels could be tuned to considerably different values by controlling the aerogel density. Upon applying a strain of 30% and 60% to the graphene/CNT aerogel with a density of 37.8 mg cm−3, its strain-gauge sensitivities (gauge factor) reached 230% and 125%, respectively, which were superior to most of carbon-based compressible conductors.

Fabrication and evaluation of artemisinin-imprinted composite membranes by developing a surface functional monomer-directing prepolymerization system.

Inspired by a surface functional monomer-directing prepolymerization system, a straightforward and effective synthesis method was first developed to prepare highly regenerate and perm-selective molecularly imprinted composite membranes of artemisinin (Ars) molecules. Attributing to the formation of the prepolymerization system, Ars molecules are attracted and bound to the membrane surface, hence promoting the growth of homogeneous and high-density molecular recognition sites on the surface of membrane materials. Afterward, a two-step-temperature imprinting procedure was carried out to prepare the novel surface functional monomer capping molecularly imprinted membranes (FMIMs). The as-prepared FMIMs not only exhibited highly adsorption capacity (11.91 mg g(-1)) but also showed an outstanding specific selectivity (imprinting factor α is 4.50) and excellent perm-selectivity ability (separation factor β is 10.60) toward Ars molecules, which is promising for Ars separation and purification.

Improving the cyclability of lithium–sulfur batteries by coating PPy onto the graphene aerogel-supported sulfur

The graphene aerogel/sulfur/polypyrrole composite with a three-dimensional (3D) porous structure was prepared by the impregnation of sulfur into graphene aerogel and then the electro-polymerization of polypyrrole on the surface of sulfur. For this composite, the 3D porous graphene aerogel provides an interconnected conductive framework to improve the electron conductivity and the utilization of sulfur. The encapsulation of polypyrrole on the sulfur can restrict the polysulfide diffusion and enhance the cycling stability of the lithium–sulfur battery. The micro-structure characterization confirms the homogeneous dispersion of sulfur and polypyrrole on the graphene aerogel backbone. The graphene aerogel/sulfur/polypyrrole composite cathode with a sulfur content of 73 wt% presents an initial discharge capacity of 1288 mA h g−1 and maintains 1017 mA h g−1 after 100 charge–discharge cycles at 0.5C, which is much higher than that of the composite lacking polypyrrole.

A fluorophosphate glass–ceramic electrolyte with superior ionic conductivity and stability for Na-ion batteries

All solid-state sodium-ion electrolytes have attracted increasing attention due to their wide range of applications in secondary batteries. Here, a new fluorophosphate glass–ceramic electrolyte, (Na2O + NaF)–TiO2–B2O3–P2O5–ZrF4 (NTBPZ), has been proposed and synthesized. Due to a low activation energy of 13.9 kJ mol−1 and reduced resistance at the grain boundaries, the NTBPZ glass ceramic has a room-temperature ionic conductivity as high as 3 × 10−5 S cm−1. In addition, the NTBPZ electrolyte has excellent thermal and chemical stabilities under ambient conditions. These outstanding performances make the NTBPZ a promising electrolyte for all-solid-state sodium-ion batteries.

Selective electroless coating of palladium nanoparticles on metallic single-walled carbon nanotube

The selective electroless coating of palladium (Pd) nanoparticles on metallic single-walled carbon nanotube (SWNT) was studied. The remarkable increase in conductivity of SWNT/Pd films up to fourfold higher than pure SWNT was due to p-type doping and Ohmic contact. Metallic behavior of SWNT/Pd-Field effect transistor (on/off ratio=1.2) was attributed to more hole carriers and no electrostatic barrier between nanotube and Pd. G-band and radial breathing mode in Raman indicates a definitive increase in the proportion of metallic SWNT. Results indicate Pd are selectively coated on metallic SWNT with more negative potential allowing for the electroless Pd2+ reduction.

A wavelength encoded optical fiber sensor based on multimode interference in a coreless silica fiber

A wavelength encoded optical fiber sensor using a three-segmented fiber structure is proposed. The device consists of a coreless silica fiber (CSF) which is coated with a thin film and spliced between two standard single-mode fibers (SMFs), forming a SMF-CSF-SMF (SCS) structure. When light is transmitted from the SMF into the CSF, the LP01 mode in the SMF is coupled to the LP0n modes, and a multimode interference occurs in the CSF. These modes interact with the thin film, hence the thickness and refractive index of the thin film can affect the modal interference. We analyze the transmission spectra of the SCS structure to obtain the characteristics of the sensor including sensing sensitivity. Numerical simulations are carried out by using the Beam Propagation Method (BPM) to investigate the multimode interference in the SCS. Two different conditions are considered in our studies: 1) changing the refractive index of a fixed-thickness film, and 2) varying the film thickness with certain refractive index. It has been found that the wavelength corresponding to the minimum output power increases 0.33509 nm when the refractive index changes every 0.01 from 1.33 up to 1.40, and 6.760 nm when the thickness enhances form 0 to 1000 nm. The trend of the raise is mostly linear for the former simulation, but gets slower and slower for the latter. The SCS structure can serve as a fiber platform for non-labeling bio-sensing when a bio-film is coated to the CSF.

Graphene/MnO2 aerogel with both high compression-tolerance ability and high capacitance, for compressible all-solid-state supercapacitors

Foam-like graphene with attractive characteristics has been proposed as a promising electrode configuration for compressible supercapacitors. However, current foam-like graphene electrodes are limited by either low compressibility or low capacity. Herein, we used a superelastic graphene aerogel as a conductive backbone and deposited pseudocapacitive materials (MnO2) into it to obtain a novel compressible electrode with both high compression-tolerance ability and high capacitance. The as-prepared graphene/MnO2 aerogel withstands 90% repeated compression cycling without any structural collapse and peel-off of MnO2 spheres from the graphene cell walls. All-solid-state supercapacitors based on graphene/MnO2 aerogel electrode were assembled to evaluate the electrochemical performances. The gravimetric capacitance of graphene/MnO2 aerogel reaches 320 F g−1 and can retain 94% even under 90% compressive strain. Moreover, a volumetric capacitance of 66.1 F cm−3 is achieved, which is much higher than that of other carbon-based compressible electrodes. Furthermore, several compressible all-solid-state supercapacitors can be integrated and connected in series to enhance the overall output voltage, which offers the potential to meet the needs of practical applications.

Neural network-based Chinese ink-painting art style learning

For purposes of intelligent art creation and existed painting style reusing, we presents a neural network-based Chinese ink-painting art style learning method, which is quite different from the traditional “pixel-wise” or “sample-wise” style transferring work. We first give a generalized definition for style features of Chinese ink painting, and then establish the style learning mechanisms with combination of back propagation neural network and image analysis techniques. The paralyzed global style features from input painting are analyzed by the well trained style learning system, the learning outputs are extracted from style information library for Chinese painting. The experiment results show that the method works well, and it is obviously a new exploration for painting style learning.