Recent Structure development of poly(vinylidene fluoride)-based piezoelectric nanogenerator for self-powered sensor

As the internet of things (IoT) era approaches, various sensors, and wireless electronic devices such as smartphones, smart watches, and earphones are emerging. As the types and functions of electronics are diversified, the energy consumption of electronics increases, which causes battery charging and maintenance issues. The piezoelectric nanogenerator (PENG) received great attention as an alternative to solving the energy issues of future small electronics. In particular, polyvinylidene fluoride (PVDF) piezoelectric polymer-based PENGs are strong potential candidate with robust mechanical properties and a high piezoelectric coefficient. In this review, we summarize the recent significant advances of the development of PVDF-based PENGs for self-powered energy-harvesting systems. We discuss the piezoelectric properties of the various structures of PVDF-based PENGs such as thin film, microstructure, nanostructure, and nanocomposite. © 2020 by the authors.1

Recent Structure Development of Poly(vinylidene fluoride)-Based Piezoelectric Nanogenerator for Self-Powered Sensor

As the internet of things (IoT) era approaches, various sensors, and wireless electronic devices such as smartphones, smart watches, and earphones are emerging. As the types and functions of electronics are diversified, the energy consumption of electronics increases, which causes battery charging and maintenance issues. The piezoelectric nanogenerator (PENG) received great attention as an alternative to solving the energy issues of future small electronics. In particular, polyvinylidene fluoride (PVDF) piezoelectric polymer-based PENGs are strong potential candidate with robust mechanical properties and a high piezoelectric coefficient. In this review, we summarize the recent significant advances of the development of PVDF-based PENGs for self-powered energy-harvesting systems. We discuss the piezoelectric properties of the various structures of PVDF-based PENGs such as thin film, microstructure, nanostructure, and nanocomposite

High Performance and Direct Current Piezoelectric Nanogenerators Using Lithium-Doped Zinc Oxide Nanosheets

The wurtzite structured zinc oxide has been studied extensively because of its unique characteristics, such as transparency, semiconducting properties, and excellent piezoelectricity. However, the defects that are inevitably present in ZnO grown by the aqueous solution method generate excessive free electrons, which reduce the piezoelectric potential by the screening effect, thus reducing the piezoelectric output performance. Herein, direct current high-performance piezoelectric nanogenerators (PENGs) based on Li-doped ZnO nanosheets are demonstrated. Doping with the p-type dopant Li reduces the number of free electrons in ZnO, minimizing the screening effect and improving the piezoelectric output performance. First, Li-doped ZnO nanosheet is synthesized at various Li concentrations using the aqueous solution method. The doping effect on the morphology and crystal structure of the ZnO nanosheet is investigated via scanning electron microscopy and X-ray diffraction. X-ray photoelectron spectroscopy confirmed that the ZnO nanosheet is doped with lithium. The Li-doped ZnO nanosheet-based PENG produce an output power of 6.552 mW cm−2, that is, a 16-fold enhancement in output power compared to that of the undoped ZnO nanosheet-based PENGs. © 2023 Wiley-VCH GmbH.FALS

Direct-current flexible piezoelectric nanogenerators based on two-dimensional ZnO nanosheet

Direct current (DC) power generation of piezoelectric nanogenerator (PNG) is promising for the realization of future self-powered electronics. Wurtzite structured two-dimensional (2-D) piezoelectric zinc oxide (ZnO) nanosheets can convert mechanical energy into electrical energy, and it produce DC output power. In this present work, we report DC power generation of PNGs based on the 2-D ZnO nanosheets. The growth condition has been optimized for the power generation, and effects of the surface morphologies and orientations have been investigated. The optimized PNGs produced voltage, current density and power density of up to 0.9 V, 16.5 μA cm−2 and 600 nW cm−2, respectively, for over 4000 cycles upon 4 kgf of force. © 2020 Elsevier B.V.1

Recent Advances in Catalytic [3,3]-Sigmatropic Rearrangements

Carbon–carbon bond formation by [3,3]-sigmatropic rearrangement is a fundamental and powerful method that has been used to build organic molecules for a long time. Initially, Claisen and Cope rearrangements proceeded at high temperatures with limited scopes. By introducing catalytic systems, highly functionalized substrates have become accessible for forming complex structures under mild conditions, and asymmetric synthesis can be achieved by using chiral catalytic systems. This review describes recent breakthroughs in catalytic [3,3]-sigmatropic rearrangements since 2016. Detailed reaction mechanisms are discussed to enable an understanding of the reactivity and selectivity of the reactions. Finally, this review is inspires the development of new cascade reaction pathways employing catalytic [3,3]-sigmatropic rearrangement as related methodologies for the synthesis of complex functional molecules

Control of the Biodegradability of Piezoelectric Peptide Nanotubes Integrated with Hydrophobic Porphyrin

Diphenylalanine (FF) is a piezoelectric material that is widely known for its high piezoelectric constant, self-assembly characteristics, and ease of manufacture. Because of its biocompatible nature, it is useful for implantable applications. However, its use in real applications is challenging because it degrades too easily in the body due to its solubility in water (0.76 g/mL). Upon incorporation of hydrophobic and biocompatible porphyrins into the FF, the degradability of the piezoelectric FF and their piezoelectric nanogenerators (PENGs) is controlled. Porphyrin-incorporated FFs are also formed as piezoelectric nanostructures well aligned on the substrate through self-assembly, and their piezoelectric properties are comparable to those of FF. The FF-based PENG degrades in only 5 min, whereas the FF-porphyrin-based PENG produces a stable output for >15 min in phosphatebuffered saline. This strategy for realizing biodegradable functional materials and devices with tunable degradation rates in the body can be applied to many implantable electronics.FALS

Electrostatic discharge prevention system via body potential control based on a triboelectric nanogenerator

In modern society, electrostatic discharge (ESD) is frequently caused by humans charged with positive charges by contact electrification, wherein natural grounding is difficult. ESD not only makes our skin uncomfortable but can also lead to the destruction of small electronic components, fires, and explosions. Therefore, there is a continuous demand for technology, such as an ungrounded anti-static method, to prevent static electricity as the grounding method is inconvenient. This study demonstrates an ESD prevention system (EPS) using a triboelectric nanogenerator (TENG), which is ungrounded and does not require an additional power source. The developed EPS prevents ESD by supplying the negative charges generated from TENGs to the human body. Various factors were investigated to optimize the performance of the EPS. Using the TENG-based EPS, the electric potential that raised to 200, 500, and 1000 V was reduced to 0 V within 20, 31, and 38 s, respectively. Additionally, it succeeded in maintaining the electric potential of a body in a stable state by supplying negative charges generated by TENG, which is operated by the mechanical energy of the human body to compensate for the positive charges generated by contact electrification. This study provides a new design for ESD prevention devices that can be utilized in various industrial units, including semiconductors, petrochemicals, and chemicals, and for the general public. © 2022 Elsevier LtdFALS

Self-assembly of unidirectionally polarized piezoelectric peptide nanotubes using environmentally friendly solvents

Diphenylalanine (FF) peptide nanotubes are considered to be particularly promising biomaterials for bio-implantable devices due to their unique characteristics, such as strong piezoelectricity, remarkable physical properties, and chemical stability. However, the 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP)-water co-solvent system, which is often used for FF nanotube synthesis, is toxic and expensive. These are limitations for the development of eco-friendly and practical biocompatible piezoelectric devices. In this study, we developed an eco-friend and cost-effective approach for aligning piezoelectric FF nanotubes using an ethanol–water solvent system. First, we fabricated horizontally aligned FF nanotubes via a meniscus-driven self-assembly process. The fabricated FF nanotubes using ethanol exhibited unidirectional polarization and strong piezoelectric properties comparable to HFIP solvent based FF nanotubes. In addition, the FF-based piezoelectric nanogenerator generates voltage, current, and power of up to 1.66 V, 19.4 nA, and 19.2 nW, respectively, with a force of 40 N. These FF-based piezoelectric nanogenerators will be applicable as a compatible energy source for future biomedical applications. © 2023 Elsevier B.V.FALS

Functionalized thermoplastic polyurethane with tunable tribopolarity and biodegradability for high performance and biodegradable triboelectric nanogenerator

Triboelectric nanogenerators (TENGs) convert mechanical energy into electrical energy and have received considerable attention as a green energy technology to solve recently emerging global environmental issues. However, most high-power TENGs use polymers as active materials, which contributes to plastic pollution. Therefore, it is necessary to use eco-friendly and biodegradable materials while maintaining high output performance for further development of TENGs as a next-generation green energy technology. This study designs a biodegradable thermoplastic polyurethane (TPU) based on polycaprolactone diol. The TPU was modified using polydimethylsiloxane diol and a chain extender containing fluorine units, which controlled the modification, output performance, and biodegradability of the TENG. Biodegradability varies depending on the structure of the TPU, especially the chain extender. The output of the TENG fabricated based on the modified TPU was considerably increased with a voltage from 1.31 V to 74.03 V and current from 0.02 μA to 1.98 μA. Further, the maximum power density increased approximately 1423 times compared to that of the native TPU-based TENG to a value of 42.71 μW/cm2. This study provides a potential strategy for the development of environmentally friendly, high-powered next-generation TENGs by ensuring controlled biodegradability

Recent Organic Transformations with Silver Carbonate as a Key External Base and Oxidant

Silver carbonate (Ag2CO3), a common transition metal-based inorganic carbonate, is widely utilized in palladium-catalyzed C–H activations as an oxidant in the redox cycle. Silver carbonate can also act as an external base in the reaction medium, especially in organic solvents with acidic protons. Its superior alkynophilicity and basicity make silver carbonate an ideal catalyst for organic reactions with alkynes, carboxylic acids, and related compounds. This review describes recent reports of silver carbonate-catalyzed and silver carbonate-mediated organic transformations, including cyclizations, cross-couplings, and decarboxylations