Recent findings demonstrate that cellulose, a highly abundant, versatile, sustainable, and inexpensive material, can be used in the preparation of very stable and flexible electrochemical energy ...storage devices with high energy and power densities by using electrodes with high mass loadings, composed of conducting composites with high surface areas and thin layers of electroactive material, as well as cellulose‐based current collectors and functional separators. Close attention should, however, be paid to the properties of the cellulose (e.g., porosity, pore distribution, pore‐size distribution, and crystallinity). The manufacturing of cellulose‐based electrodes and all‐cellulose devices is also well‐suited for large‐scale production since it can be made using straightforward filtration‐based techniques or paper‐making approaches, as well as utilizing various printing techniques. Herein, the recent development and possibilities associated with the use of cellulose are discussed, regarding the manufacturing of electrochemical energy storage devices comprising electrodes with high energy and power densities and lightweight current collectors and functional separators.
The recent progress of cellulose, as an appealing natural material that can outperform traditional synthetic materials, for use in energy‐storage devices is described. Cellulose can bring benefits in the fabrication and properties of energy‐storage materials and devices, eventually enabling significant improvements in electrochemical performance, mechanical flexibility, cost competitiveness, and form factors, which are difficult to achieve with conventional power source technologies.
Biomolecular piezoelectric materials are considered a strong candidate material for biomedical applications due to their robust piezoelectricity, biocompatibility, and low dielectric property. The ...electric field has been found to affect tissue development and regeneration, and the piezoelectric properties of biological materials in the human body are known to provide electric fields by pressure. Therefore, great attention has been paid to the understanding of piezoelectricity in biological tissues and its building blocks. The aim herein is to describe the principle of piezoelectricity in biological materials from the very basic building blocks (i.e., amino acids, peptides, proteins, etc.) to highly organized tissues (i.e., bones, skin, etc.). Research progress on the piezoelectricity within various biological materials is summarized, including amino acids, peptides, proteins, and tissues. The mechanisms and origin of piezoelectricity within various biological materials are also covered.
The piezoelectricity of the various elements constituting the human body has attracted intensive attention, due to the strong piezoelectricity, biocompatibility, low dielectric, and tissue regeneration effects. Research progress in the various biological piezoelectric materials from the basic building blocks to organized tissues are summarized. The mechanisms and origins of piezoelectricity are discussed, and challenges and perspectives for developing biological piezoelectric materials are presented.
In this work, a sulfur (S) vacancy passivated monolayer MoS2 piezoelectric nanogenerator (PNG) is demonstrated, and its properties before and after S treatment are compared to investigate the effect ...of passivating S vacancy. The S vacancies are effectively passivated by using the S treatment process on the pristine MoS2 surface. The S vacancy site has a tendency to covalently bond with S functional groups; therefore, by capturing free electrons, a S atom will form a chemisorbed bond with the S vacancy site of MoS2. S treatment reduces the charge‐carrier density of the monolayer MoS2 surface, thus the screening effect of piezoelectric polarization charges by free carrier is significantly prevented. As a result, the output peak current and voltage of the S‐treated monolayer MoS2 nanosheet PNG are increased by more than 3 times (100 pA) and 2 times (22 mV), respectively. Further, the S treatment increases the maximum power by almost 10 times. The results suggest that S treatment can reduce free‐charge carrier by sulfur S passivation and efficiently prevent the screening effect. Thus, the piezoelectric output peaks of current, voltage, and maximum power are dramatically increased, as compared with the pristine MoS2.
Piezoelectricity of sulfur vacancy passivated MoS2 nanosheets is much higher than that of pristine MoS2 nanosheets. Sulfur vacancies can be filled through a sulfur treatment and the resulting output power of the device generates a 10‐times higher power. This result offers a new approach to realize a MoS2 nanosheet‐based high‐performance piezoelectric nanogenerator for self‐powered wearable electronics.
Here micropatterned poly(vinylidenefluoride‐co‐trifluoroethylene) (P(VDF‐TrFE)) films‐based piezoelectric nanogenerators (PNGs) with high power‐generating performance for highly sensitive ...self‐powered pressure sensors are demonstrated. The microstructured P(VDF‐TrFE)‐based PNGs reveal nearly five times larger power output compared to a flat film‐based PNG. The micropatterning of P(VDF‐TrFE) polymer makes itself ultrasensitive in response to mechanical deformation. The application is demonstrated successfully as self‐powered pressure sensors in which mechanical energy comes from water droplet and wind. The mechanism of the high performance is intensively discussed and illustrated in terms of strain developed in the flat and micropatterned P(VDF‐TrFE) films. The impact derived from the patterning on the output performance is studied in term of effective pressure using COMSOL multiphysics software.
Micropatterned poly(vinylidenefluoride‐co‐trifluoroethylene) P(VDF‐TrFE) film‐based piezoelectric nanogenerators with high power‐generating performance for highly sensitive self‐powered pressure sensors are successfully demonstrated. The microstructured P(VDF‐TrFE)‐based PNGs have nearly five times larger power output compared to the flat film‐based PNG. The microstructured nanogenerator efficiently converts external force into electric output with superior mechanical durability under various circumstances, such as rain drops and wind blow.
Here, a composite material based on the butylated melamine formaldehyde (BMF) and high permittivity CaCu3Ti4O12 (CCTO) particles as a triboelectric dielectric material for stable high output ...triboelectric nanogenerators (TENGs) is proposed. CCTO particles, which have the high permittivity of 7500, can potentially result in the formation of strong internal polarization into the dielectric material under the electric field from triboelectric charges. As a consequence, the charge induction on the bottom electrode is enhanced thereby increasing the triboelectric output performance. A rotation‐type freestanding mode TENG based on BMF–CCTO 1 wt% composite material demonstrates high performance power output of a root‐mean‐square voltage and current density with 268 V and 25.8 mA m−2, respectively. The strategy of incorporating the high permittivity CCTO particles can be universally applied to any triboelectric polymer matrix in order to enhance the output performance of TENGs.
High performance triboelectric nanogenerators with high permittivity CaCu3Ti4O12 particles on a polymer matrix are demonstrated. CaCu3Ti4O12 particles induce strong internal polarization in the polymer matrix under an electric field generated by triboelectric charges, thereby enhancing triboelectric output. The strategy of incorporating high permittivity particles into a polymer matrix is a facile and effective way to achieve high power output from triboelectric nanogenerators.
Recently, piezoelectricity has been observed in 2D atomically thin materials, such as hexagonal‐boron nitride, graphene, and transition metal dichalcogenides (TMDs). Specifically, exfoliated ...monolayer MoS2 exhibits a high piezoelectricity that is comparable to that of traditional piezoelectric materials. However, monolayer TMD materials are not regarded as suitable for actual piezoelectric devices due to their insufficient mechanical durability for sustained operation while Bernal‐stacked bilayer TMD materials lose noncentrosymmetry and consequently piezoelectricity. Here, it is shown that WSe2 bilayers fabricated via turbostratic stacking have reliable piezoelectric properties that cannot be obtained from a mechanically exfoliated WSe2 bilayer with Bernal stacking. Turbostratic stacking refers to the transfer of each chemical vapor deposition (CVD)‐grown WSe2 monolayer to allow for an increase in degrees of freedom in the bilayer symmetry, leading to noncentrosymmetry in the bilayers. In contrast, CVD‐grown WSe2 bilayers exhibit very weak piezoelectricity because of the energetics and crystallographic orientation. The flexible piezoelectric WSe2 bilayers exhibit a prominent mechanical durability of up to 0.95% of strain as well as reliable energy harvesting performance, which is adequate to drive a small liquid crystal display without external energy sources, in contrast to monolayer WSe2 for which the device performance becomes degraded above a strain of 0.63%.
WSe2 bilayers with turbostratic stacking have reliable piezoelectric properties that cannot be obtained from a WSe2 monolayer. The flexible piezoelectric WSe2 bilayers exhibit a prominent mechanical durability of up to 0.95% of strain as well as reliable energy harvesting performance, which is adequate to drive a small liquid crystal display without external energy sources.
Nanomaterials with antioxidant properties are promising for treating reactive oxygen species (ROS)‐related diseases. However, maintaining efficacy at low doses to minimize toxicity is a critical for ...clinical applications. Tuning the surface strain of metallic nanoparticles can enhance catalytic reactivity, which has rarely been demonstrated in metal oxide nanomaterials. Here, it is shown that inducing surface strains of CeO2/Mn3O4 nanocrystals produces highly catalytic antioxidants that can protect tissue‐resident stem cells from irradiation‐induced ROS damage. Manganese ions deposited on the surface of cerium oxide (CeO2) nanocrystals form strained layers of manganese oxide (Mn3O4) islands, increasing the number of oxygen vacancies. CeO2/Mn3O4 nanocrystals show better catalytic activity than CeO2 or Mn3O4 alone and can protect the regenerative capabilities of intestinal stem cells in an organoid model after a lethal dose of irradiation. A small amount of the nanocrystals prevents acute radiation syndrome and increases the survival rate of mice treated with a lethal dose of total body irradiation.
Inducing surface strains of CeO2/Mn3O4 nanocrystals produces highly catalytic antioxidants that are powerful enough to protect intestinal stem cells from irradiation‐induced reactive oxygen species damage. Only a small dose of the CeO2/Mn3O4 nanocrystals prevents acute radiation syndrome in a human intestinal organoid model and increases survival rate of mice treated with a lethal dose of total body irradiation.
A synthesis strategy for the preparation of ultrathin free‐standing ternary‐alloy nanosheets is reported. Ultrathin Pd‐Pt‐Ag nanosheets with a thickness of approximately 3 nm were successfully ...prepared by co‐reduction of the metal precursors in an appropriate molar ratio in the presence of CO. Both the presence of CO and the interplay between the constituent metals provide fine control over the anisotropic two‐dimensional growth of the ternary‐alloy nanostructure. The prepared Pd‐Pt‐Ag nanosheets were superior catalysts of ethanol electrooxidation owing to their specific structural and compositional characteristics. This approach will pave the way for the design of multicomponent 2D nanomaterials with unprecedented functions.
Ultrathin Pd‐Pt‐Ag nanosheets with a thickness of approximately 3 nm were successfully prepared by the co‐reduction of suitable metal precursors in an appropriate molar ratio in the presence of CO. These nanosheets are superior catalysts of ethanol electrooxidation owing to their specific structural and compositional characteristics.
Hydrophobic sponge structure‐based triboelectric nanogenerators using an inverse opal structured film for sustainable energy harvesting over a wide range of humid atmosphere have been successfully ...demonstrated. The output voltage and current density reach a record value of 130 V and 0.10 mA cm−2, respectively, giving over 10‐fold power enhancement, compared with the flat film‐based triboelectric nanogenerator.
Air-transmitted pathogens may cause severe epidemics showing huge threats to public health. Microbial inactivation in the air is essential, whereas the feasibility of existing air disinfection ...technologies meets challenges including only achieving physical separation but no inactivation, obvious pressure drops, and energy intensiveness. Here we report a rapid disinfection method toward air-transmitted bacteria and viruses using the nanowire-enhanced localized electric field to damage the outer structures of microbes. This air disinfection system is driven by a triboelectric nanogenerator that converts mechanical vibration to electricity effectively and achieves self-powered. Assisted by a rational design for the accelerated charging and trapping of microbes, this air disinfection system promotes microbial transport and achieves high performance: >99.99% microbial inactivation within 0.025 s in a fast airflow (2 m/s) while only causing low pressure drops (<24 Pa). This rapid, self-powered air disinfection method may fill the urgent need for air-transmitted microbial inactivation to protect public health.
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