Linear-grating hybridized electromagnetic-triboelectric nanogenerator for sustainably powering portable electronics

Utilizing a nanogenerator to scavenge mechanical energy from our living environment is an effective method to solve the power source issue of portable electronics. We report a linear-grating hybridized electromagnetic-triboelectric nanogenerator for scavenging the mechanical energy generated from sliding motions to sustainably power certain portable electronics. The hybridized nanogenerator consists of a slider and a stator in the structural design, and possesses a 66-segment triboelectric nanogenerator (TENG) and a 9-segment electromagnetic generator (EMG) in the functional design. At a sliding acceleration of 20 m/s², the hybridized nanogenerator can deliver maximum powers of 102.8 mW for the TENG at a loading resistance of 0.4 MΩ and 103.3 mW for the EMG at a loading resistance of 6 kΩ. With an optimal hybridized combination of the TENG with a transformer and the EMG with a power management circuit, a 10 mF capacitor can be easily charged to 2.8 V in 20 s. A packaged hybridized nanogenerator with a light weight of 140 g and small dimensions of 12 cm × 4 cm × 1.6 cm excels in scavenging low-frequency sliding energy to sustainably power portable electronics.

Open image in new window

     

Advanced 3D printing-based triboelectric nanogenerator for mechanical energy harvesting and self-powered sensing

Triboelectric nanogenerator (TENG) is an innovative technology that it has sparked a revolution in distributed energy supply and self-powered system. Integration of advanced TENG with burgeoning 3D printing (3DP) technologies fosters the emergence of 3DP-based TENGs. It will inevitably promote the rapid development and widespread applications of next-generation portable electronics and multifaceted artificial intelligence. However, due to the different subject field between researchers specializing in TENG and those good at 3DP, they are not always a perfect combination. It is rather difficult to achieve with both excellent electrical properties and outstanding practical performances. For that, a review is presented more systematic and comprehensive of 3DP-based TENGs for the first time. In which the quantitatively statistics and correlation data of research progress are given, such as publications, 3DP technologies and materials, structure designs and functionalities, working modes and mechanisms, output performances, unique advantages, potential technical challenges and promising application fields that can impede their sizable production and applications are discussed. It is hoped that this review will not only deepen the intersection and amalgamation between 3DP and TENGs, but also push forward more in-depth research and applications of future TENGs.     

Theoretical Comparison,Equivalent Transformation,and Conjunction Operations of Electromagnetic Induction Generator and Triboelectric Nanogenerator for Harvesting Mechanical Energy

Triboelectric nanogenerator (TENG) is a newly invented technology that is effective using conventional organic materials with functionalized surfaces for converting mechanical energy into electricity, which is light weight, cost‐effective and easy scalable. Here, we present the first systematic analysis and comparison of EMIG and TENG from their working mechanisms, governing equations and output characteristics, aiming at establishing complementary applications of the two technologies for harvesting various mechanical energies. The equivalent transformation and conjunction operations of the two power sources for the external circuit are also explored, which provide appropriate evidences that the TENG can be considered as a current source with a large internal resistance, while the EMIG is equivalent to a voltage source with a small internal resistance. The theoretical comparison and experimental validations presented in this paper establish the basis of using the TENG as a new energy technology that could be parallel or possibly equivalently important as the EMIG for general power application at large‐scale. It opens a field of organic nanogenerator for chemists and materials scientists who can be first time using conventional organic materials for converting mechanical energy into electricity at a high efficiency.     

Trefftz solutions for piezoelectricity by Lekhnitskii's formalism and boundary‐collocation method

In this paper, a solution procedure for plane piezoelectricity is developed by Trefftz boundary‐collocation method. Starting with the general plane piezoelectricity solution derived by Lekhnitskii's formalism, the basic sets of Trefftz functions which satisfy the homogeneous governing equations are derived. Moreover, special sets of Trefftz functions are derived for impermeable elliptical voids, impermeable sharp cracks and permeable sharp cracks with arbitrary orientations with respect to the material poling direction. The functions in the special sets satisfy not only the homogeneous governing equations but also the boundary conditions at the peripheries of the pertinent defects. By adopting Trefftz functions as the trial functions, multi‐domain Trefftz boundary‐collocation method is formulated. Numerical examples are presented to illustrate the efficacy of the formulation. Copyright © 2005 John Wiley & Sons, Ltd.     

Advanced triboelectric materials for liquid energy harvesting and emerging application

Triboelectric properties of materials play an essential role in liquid energy harvesting and emerging application. The triboelectric properties of materials can be controlled by chemical functionalization strategy, which can improve the utilization of liquid energy resources or reduce the hazards of electrostatic effects. Herein, the latest research progress in molecular modification based on chemical functionalization to control triboelectric properties of materials is systematically summarized. By introducing the mechanism of contact electrification between liquid and solid materials and the developmental history of liquid–solid contact electrification, the influence of solid surface charge density, wettability and liquid properties on contact electrification of liquid and solid materials is described. Research progress on chemical functionalization for improving the hydrophobicity of solid materials, surface charge density of solid materials and triboelectric properties of liquid materials is highlighted. The focus then turns to the significance of enhanced liquid–solid contact electrification in energy harvesting, self-powered sensors and metal corrosion protection. Recent advances in chemical functionalization strategies for weakening the triboelectric properties of solid and liquid materials are also highlighted. Finally, an outlook of the potential challenges for developing chemical functionalization strategies in the field of solid surface modification and liquid molecular modification is presented.     

Design of SiO2/PMHS hybrid nanocomposite for surface treatment of cement-based materials

A silica-based hybrid nanocomposite, SiO₂/polymethylhydrosiloxane (SiO₂/PMHS), is synthesized by a sol-gel process and used for surface treatment of hardened cement-based materials. The advantages of both normal organic and inorganic silica-based treatment agents are explored. Results revealed a covalent chemical bonding of SiO₂ and PMHS and the SiO₂/PMHS showed hydrophobicity and pozzolanic reactivity when used for surface treatment. Greater reductions of the water absorption rate and gas permeability coefficient of cement-based materials were achieved by the hybrid nanocomposite compared to its individual components, showing synergistic effects of hydrophobicity and pore refinement characteristics as proved by the measurements of the contact angle, the mineralogy, the morphology and the porosity. The results showed promising advantages of using silica-based hybrid nanocomposite for surface treatment to achieve a higher surface quality. Moreover, it can be suggested that more functionalities of the cement-based materials can be tailored through the design and use of the silica-based hybrid materials.     

压电式纳米发电机及其混合器件的研究进展

随着化石能源的过度使用和开采,随之而来的能源和环境问题也日益尖锐,而人们对能源的需求不减反增,因此寻求一种新型的绿色可持续能源是非常必要的。环境中的能量十分丰富,因此从环境中收集能量进行转化是十分有前景的方法。压电材料在受到外界作用发生机械变形时,能实现机械能向电能的转化,因此,压电式纳米发电机作为一种潜在的可持续、绿色能源,近年来受到广泛关注。从压电材料的分类入手,结合其制备方法、结构和性能等,对近年来一些研究成果进行了概述,详细评价了不同制备方法、结构对压电式纳米发电机压电性能的影响,并对今后发展进行了展望。     

Optical nonlinearity of CdSe-PMMA hybrid nanocomposite investigated via Z-scan technique and semi-empirical relations

CdSe-PMMA nanocomposite has been synthesized by ex-situ technique. The effect of different Ag doping concentrations on its structural and optical properties has been studied. X-ray diffraction reveals the hexagonal wurtzite structure of the polymer nanocomposites with preferential growth of the nanocrystals along (1 0 0) direction. Transmission electron micrograph shows the spherical CdSe nanoparticles embedded in polymer matrix. The nonlinear refractive index of the nanocomposites has been calculated using Tichy & Ticha semi-empirical relations and Z-scan technique. Z-scan results disclose the two photon absorption process in the hybrid nanocomposites with self focussing behaviour. With Ag doping, the nonlinearity is found to be increased up to 0.2% Ag doping concentration due to the confined effect of Surface Plasmon, Quantum confinement and thermal lensing. Above 0.2% Ag concentration, its value decreases due to the declined linear refractive index of the nanocomposites. Maximum two photon figure of merit is 76 for 0.2% Ag doped CdSe-PMMA hybrid nanocomposite. The present results accentuate the possibility of tuning the optical non-linearity of CdSe-PMMA hybrid nanocomposite by adjusting the doping concentration.     

Control of Halogen Atom in Inorganic Metal-Halide Perovskites Enables Large Piezoelectricity for Electromechanical Energy Generation

Regulating the strain of inorganic perovskites has emerged as a critical approach to control their electronic and optical properties. Here, an alternative strategy to further control the piezoelectric properties by substituting the halogen atom (I/Br) in the CsPbX₃ perovskite (X = Cl, Br) structure is adopted. A series of piezoelectric materials with excellent piezoelectric coefficients (d₃₃) are unveiled. Iodine-incorporated CsPbBr₂I demonstrates the record intrinsic piezoelectric response (d₃₃ ≈47 pC N⁻¹) among all inorganic metal halide perovskites. This leads to an excellent electrical output power of ≈ 0.375 mW (24.8 µW cm⁻² N⁻¹) in the piezoelectric energy generator (PEG) which is higher than those of the pristine/mixed perovskite references with CsPbX₃ (X = I, Br, Cl). With its structural phase remaining unchanged, the strained CsPbBr₂I retains its superior piezoelectricity in both thin film and nanocrystal powder forms, further demonstrating its repeatability and versatility of applications. The origin of high piezoelectricity is found to be due to halogen-induced anisotropic lattice strain in the unit-cell along the c-axis, and octahedral distortion. This study reveals an avenue to design new piezoelectric materials by modifying their halide constituents and paves the way to design efficient PEGs for improved electromechanical energy conversion.     

Preparation and optical limiting properties of a POSS-containing organic-inorganic hybrid nanocomposite

A novel POSS-containing organic-inorganic hybrid nanocomposite (P) was prepared by the Pt-catalyzed hydrosilylation reaction of octahydridosilsesquioxane (T₈^H) with substituted acetylene, CH≡CCH₂O-C₆H₄-COO-C₆H₄-p-NN-C₆H₄-p-OCH₃ (M). The hybrid nanocomposite was soluble in common solvents such as CHCl₃, THF, toluene and C₂H₄Cl₂. Its structure was characterized by FT-IR, ¹H NMR, and ²⁹Si NMR, respectively. Optical limiting property was evaluated by a Q-switched Nd:YAG laser system with a wavelength of 532 nm, 4 ns pulse width and a repetition of 1 Hz. The result shows that the POSS-based organic-inorganic hybrid nanocomposite exhibits novel optical limiting property, well photo and high thermal stability (T_d, temperature for 5% weight loss, as high as 319 °C). The optical limiting property increases with the increase of solution concentration.     

Thermal and optical properties of poly(methyl methacrylate)/calcium carbonate nanocomposite

The study deals with thermal and optical properties of poly(methyl methacrylate) (PMMA) containing 2wt% calcium carbonate (CaCO₃) nanofiller. It was found that the thermal conductivity increases with increasing temperatures, due to thermal activation of the phonons in the PMMA/CaCO₃ nanocomposite. This enhancement in the thermal conduction is mainly attributed to the heat transferred by lattice vibrations as major contributors and electrons as minor contributors during thermal conduction. The optical properties were investigated as a function of wavelength and photon energy of UV radiation. The optical results obtained were analysed in terms of absorption formula for noncrystalline materials. It was found that the measured optical energy gap for the pure PMMA is greater than the PMMA/CaCO₃ nanocomposite. The width of the energy tails of the localised states was calculated. Adding CaCO₃ nanofiller into PMMA matrix may cause the localised states of different colour centres to overlap and extend in the mobility gap. This overlap may give an evidence for decreasing energy gap when adding CaCO₃ nanofiller in the polymer matrix.     

Experimental study on heat transfer and rheological characteristics of hybrid nanofluids for cooling applications

The enhancement of heat transfer and rheological behaviour of hybrid nanofluids (HyNF) flowing through the tubular heat exchanger system were experimentally analysed. In this study, the effects of Nusselt number, Peclet number, Reynolds number, heat transfer coefficient and pressure drop were investigated for various volume concentrations of copper-titania hybrid nanocomposite (HyNC). The experiments were performed for various HyNC volume concentrations in the base fluid (cold water) ranging from 0.1% to 1.0%. The experimental results showed that the convective heat transfer coefficient of the HyNF increased by 59.3% for the particular volume concentration of 0.7% of HyNC. The friction factor and pressure drop of HyNF for 1.0% volume concentration were expected to be 0.8% and 5.4%, respectively. This implies for experiencing penalty in the pumping capacity. The experimental measurements, on the other hand, were validated using a newly developed correlation. For all the volume concentrations of HyNF, the deviation obtained for the experimental data and the prediction was observed to be +8% and ?8%, respectively. The present correlation has been found to be in good agreement with the experimental data, which can be helpful in predicting the heat transfer characteristics of the HyNF.     

Enhanced Mechanical Energy Harvesting in Triboelectric Nanogenerator by the Reinforcement of Polypyrrole-Decorated rGO Sheets in PDMS

Energy harvesting triboelectric nanogenerators (TENGs) to scavenge unused mechanical energy have received significant attention in this decade. Herein, the development of reduced graphene oxide (rGO):polypyrrole (PPy) hybrid-modified polydimethylsiloxane (PDMS) as TENG for various device applications is reported. The bulk of PDMS is altered by different fillers such as rGO, PPy, and the binary hybrids of rGO and PPy with varying weight ratios. Among various PDMS composites, 1 wt% of 1:8 rGO:PPy–PDMS composite exhibits higher TENG responses than other PDMS composite. The superior TENG performances of 1 wt% 1:8 rGO:PPy–PDMS composite are attributed to the formation of intensified negative charges inside the PDMS matrix. This charge intensification in the composite is due to various mechanisms, including the charge trapping ability of rGO:PPy filler, microcapacitor formation by introducing hybrid filler in the system with proper conducting networks, and the electron-donating nature of PPy conducting polymer. A 3D stacked device proposed using 1 wt% 1:8 rGO:PPy–PDMS composite delivered a short-circuit current of 16 μA and an open-circuit potential of 60 V by simple palm pressing. Also, the ability of the stacked device for charging/powering portable devices and light-emitting diodes is demonstrated.     

纳米TiO2/醇酸复合涂层的耐腐蚀性能研究

采用盐雾试验和电化学交流阻抗技术,研究了纳米TiO2对钢板涂层耐腐蚀性能的影响,并通过扫描电镜观察了纳米TiO2复合涂层断面形貌.研究表明,纳米TiO2复合涂层的耐腐蚀性能均优于未添加纳米TiO2涂层,当纳米TiO2添加量为1.5%(质量分数)时,涂层耐盐雾时间由420h提高到710h,涂层阻抗值也由107Ω·cm2增加至109Ω·cm2.从涂层断面观察发现,纳米TiO2添加量为1.5%(质量分数)时,颗粒较均匀分散,粘接紧密,形成较为致密的纳米复合涂层.     

溶胶-凝胶法制备纳米复合永磁材料及其磁性

用溶胶-凝胶方法制备了一种新型纳米复合永磁材料.XRD及SEM表明,由于这种材料的软磁相与硬磁相具有30nm左右尺寸而发生强烈的交换耦合作用,导致该种新材料具有优异的磁性能.     

A Review of Mechanical and Electromechanical Properties of Piezoelectric Nanowires

Piezoelectric nanowires are promising building blocks in nanoelectronic, sensing, actuation and nanogenerator systems. In spite of great progress in synthesis methods, quantitative mechanical and electromechanical characterization of these nanostructures is still limited. In this article, the state‐of‐the art in experimental and computational studies of mechanical and electromechanical properties of piezoelectric nanowires is reviewed with an emphasis on size effects. The review covers existing characterization and analysis methods and summarizes data reported in the literature. It also provides an assessment of research needs and opportunities. Throughout the discussion, the importance of coupling experimental and computational studies is highlighted. This is crucial for obtaining unambiguous size effects of nanowire properties, which truly reflect the effect of scaling rather than a particular synthesis route. We show that such a combined approach is critical to establish synthesis‐structure‐property relations that will pave the way for optimal usage of piezoelectric nanowires.