A Sliding-Mode Triboelectric Nanogenerator with Chemical Group Grated Structure by Shadow Mask Reactive Ion Etching.

The sliding-mode triboelectric nanogenerator (S-TENG) with grated structure has important applications in energy harvest and active sensors; however its concavo-convex structure leads to large frictional resistance and abrasion. Here, we developed a S-TENG with a chemical group grated structure (S-TENG-CGG), in which the triboelectric layer's triboelectric potential has a positive-negative alternating charged structure. The triboelectric layer of the S-TENG-CGG was fabricated through a reactive ion etching process with a metal shadow mask with grated structure. In the etched region, the nylon film, originally positively charged as in friction with stainless steel, gained opposite triboelectric potential and became negatively charged because of the change of surface functional groups. The output signals of the S-TENG-CGG are alternating and the frequency is determined by both the segment numbers and the moving speed. The applications of the S-TENG-CGG in the charging capacitor and driving calculator are demonstrated. In the S-TENG-CGG, since there is no concavo-convex structure, the frictional resistance and abrasion are largely reduced, which enhances its performances in better stability and longer working time.

The phase transformation of CuInS2 from chalcopyrite to wurtzite.

In the present work, CuInS2 nanoparticles have been successfully synthesized by water-bath method with deionized water as solvent and thioglycolic acid as complexing agent at 80°C. The phase transition of CuInS2 from chalcopyrite to wurtzite was realized by adjusting the pH value of reaction solution. The emergence of Cu2S in the condition of higher pH value of reaction solution led to the formation of wurtzite CuInS2. This facile method that controls the phase structure by adjusting the solution pH value could open a new way to synthesize other I-III-VI2 ternary semiconductor compounds.

Synthesis and photoelectric properties of new Dawson-type polyoxometalate-based dimeric and oligomeric Pt(II)-acetylide inorganic-organic hybrids.

A new synthesis route for preparing Dawson-type polyoxometalate (POM) based inorganic-organic hybrid materials is presented. Two new heteropolytungstate-based dimeric and oligomeric Pt(II) acetylide inorganic-organic hybrid compounds (2PtOD and PPtOD) were prepared by Hagihara's dehydrohalogenating coupling of a terminal diacetylene POM hybrid containing diphosphoryl functionality and an appropriate platinum(II) halide precursor. This method provides a rigid covalent linkage between the POM and the organometallic Pt(II) acetylide moiety. The redox potential of the polyanion can be tuned by grafting the organic and organometallic groups on it. The photoelectric properties of hybrid LB films derived from these inorganic-organic composites were studied.

Simultaneously harvesting electrostatic and mechanical energies from flowing water by a hybridized triboelectric nanogenerator.

Flowing water contains not only mechanical kinetic energy, but also the electrostatic energy owing to the triboelectric charges caused by its contact with surrounding media such as air. In this paper, a water wheel hybridized triboelectric nanogenerator (TENG), composed of a water-TENG part and a disk-TENG part, has been developed for simultaneously harvesting the two types of energies from the tap water flowing from a household faucet. The wheel blades of the hybridized TENG are composed by superhydrophobic polytetrafluoroethylene (PTFE) thin films with nanostructures, which are used as water-TENG to harvest the electrostatic energy from the flowing water. In addition, the flowing water impacted on the wheel blades also causes the rotation motion of disk-TENG and can be used to harvest the mechanical kinetic energy. The short-circuit current of the water-TENG and the disk-TENG at a flowing water rate of 54 mL/s can reach 12.9 and 3.8 µA, respectively. The hybridized TENG is also demonstrated to harvest wind energy and acts as a self-powered sensor to detect the flowing water rate and wind speed. All these results show the potentials of the hybridized TENG for harvesting multiple types of energies from the environment.

Pulsed nanogenerator with huge instantaneous output power density.

A nanogenerator (NG) usually gives a high output voltage but low output current, so that the output power is low. In this paper, we developed a general approach that gives a hugely improved instantaneous output power of the NG, while the entire output energy stays the same. Our design is based on an off-on-off contact based switching during mechanical triggering that largely reduces the duration of the charging/discharge process, so that the instantaneous output current pulse is hugely improved without sacrificing the output voltage. For a vertical contact-separation mode triboelectric NG (TENG), the instantaneous output current and power peak can reach as high as 0.53 A and 142 W at a load of 500 Ω, respectively. The corresponding instantaneous output current and power density peak even approach 1325 A/m(2) and 3.6 × 10(5) W/m(2), which are more than 2500 and 1100 times higher than the previous records of TENG, respectively. For the rotation disk based TENG in the lateral sliding mode, the instantaneous output current and power density of 104 A/m(2) and 1.4 × 10(4) W/m(2) have been demonstrated at a frequency of 106.7 Hz. The approach presented here applies to both a piezoelectric NG and a triboelectric NG, and it is a major advance toward practical applications of a NG as a high pulsed power source.

Controllable fabrication of patterned ZnO nanorod arrays: investigations into the impacts on their morphology.

Fabricating ZnO nanorod arrays with precisely controlled morphology, alignment, and density is highly desirable but rather challenging. On the other hand, understanding the parameters that affect their final morphology and the growth mechanisms is significant to integrate such patterned ZnO nanorod arrays in various applications. Therefore, ZnO nanorod arrays with different density and morphology were fabricated by electron beam lithography (EBL) combined with the hydrothermal methods in this work. The influences of prepatterned geometry and the growth parameters such as seed layer, the precursor concentration, and the growth time on their final morphology were investigated. Under the coactions of EBL and the subsequent hydrothermal growth, ZnO nanorod arrays with precisely controlled density, position and morphology were achieved. The growth mechanism was also discussed in detail for the ZnO nanorod arrays which confined by the aperture with different size.

Effect of highly ordered single-crystalline TiO2 nanowire length on the photovoltaic performance of dye-sensitized solar cells.

One-dimensional semiconductor nanostructures grown directly onto transparent conducting oxide substrates with a high internal surface area are most desirable for high-efficiency dye-sensitized solar cells (DSSCs). Herein, we present a multicycle hydrothermal synthesis process to produce vertically aligned, single crystal rutile TiO(2) nanowires with different lengths between 1 and 8 µm for application as the working electrode in DSSCs. Optimum performance was obtained with a TiO(2) nanowire length of 2.0 µm, which may be ascribed to a smaller nanowire diameter with a high internal surface area and better optical transmittance with an increase in the incident light intensity on the N719 dye; as well as a firm connection at the FTO/TiO(2) nanowire interface.

Solution fabrication and photoelectrical properties of CuInS2 nanocrystals on TiO2 nanorod array.

One-dimensional semiconductor architectures are receiving attention in preparing photovoltaic solar cells because of its superior charge transport as well as excellent light-harvesting efficiency. In this study, vertically aligned single-crystalline TiO(2) nanorods array was grown directly on transparent conductive glass (FTO), and then CuInS(2) nanocrystals were deposited on nanorods array by spin coating method to form TiO(2)/CuInS(2) heterostructure films. The resulting nanostructure assembly and composition was confirmed by field-emission scanning electron microscope (FESEM) , transmission electron microscopy (TEM), high-resolution TEM, and X-ray diffraction(XRD). Ultraviolet-visible absorption spectroscopy (UV-vis) data indicates that the absorbance of the nanocomposite film extended into the visible region compared with bare TiO(2) nanorod arrays. The surface photovoltage spectra (SPS) also showed a new and enhanced response region corresponding to the absorption spectrum. These results suggest that the novel CuInS(2) nanocrystals sensitized TiO(2) nanorod array on FTO photoelectrodes has a potential application in photovoltaic devices.

Synthesis and photoluminescence of a full zinc blende phase ZnO nanorod array.

A single-crystalline ZnO nanorod array with rectangular cross-sections has been synthesized, in which the as-obtained products are a complete metastable zinc blende (ZB) phase. X-ray powder diffraction, electron microscopy, and elemental maps have been used to show that the ZB-ZnO samples have a lattice constant a = 4.580 Å, and are free from contamination by hexagonal wurtzite (HW) ZnO. Based on our experimental data, the associated growth mechanism is tentatively suggested. In addition, the photoluminescence (PL) spectrum (about 400 nm (3.1 eV)) of the as-fabricated ZB-ZnO products was detected; this is the first experimental report of the optical properties of ZB-ZnO nanorod arrays.

[Influence of different sol-gel system on the luminescence of nanocrystalline ZnO powder].

ZnO nanopowders were prepared by the sol-gel techniques with two kinds of solvent. Microstructure of powder samples was examined by XRD and TEM. The results indicate that the two ZnO samples have the same crystal and energy band structure. Their photoluminescence (PL) spectra in ultraviolet region are analogous, but their photoluminescence (PL) spectra in visible region are different. The reason is that the two kinds of solvent with different polarity result in the difference in configuration and distribution of the sample surface states in the two systems.

[Preparation and luminescence of CeOx/ZnO nanocomposite powders].

CeOx/ZnO nanocomposite powders were prepared by sol-gel process. The powder samples were examined by XRD, TEM, XPS and photoluminescence (PL). PL enhancement of nanocomposite powder at 502 nm compared to pure ZnO was observed when Ce3+ were present in samples. New peak at 603 nm was observed when Ce4+ were present. PL enhancement of nanocomposite powder was correlated with more oxygen vacancies which were caused by Ce3+. The new peak at 603 nm is attributed to new energy transition in the interface of CeO2/ZnO.

[Influence of different sol-gel systems on the luminescence of nanocrystalline ZnO powders].

ZnO nanopowders were prepared by the sol-gel techniques with two kinds of solvent. Microstructure of the powdersamples was examined by XRD and TEM. The results indicate that two ZnO samples have the same crystal and energy band structure. Their photolurminescence (PL) spectra in the ultraviolet region are analogous, but their photoluminescence (PL) spectra in the visible region are different. The reason is that two kinds of solvent with different polarity result in the difference in configuration and distribution of the sample surface states in the two systems.

[Study on the preparation of nanometer oxide SnO2 gas-sensitive material by sol-gel method].

Based on the sol-gel method, nanosized SnO2 material was prepared, and its structure and properties were studied by XRD, UV and Raman spectra. The XRD result indicated that the SnO2 particles had an ideal nanosize. The diameter of SnO2 particles increased with raising the temperature. The Raman spectrum indicated that the SnO2 nanometer material annealed at low temperature had a large number of O-empties. The UV spectra showed that the sample had stable absorption properties although the particle size changed greatly in the annealed range of 300-500 degrees C. These properties might be utilized in enhancing the performance of SnO2 gas-sensitive devices.