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Real-time monitoring of flow turbulence is very difficult but extremely important in fluid dynamics, which plays an important role in flight safety and control. Turbulence can cause airflow to detach at the end of the wings, potentially resulting in the aerodynamic stall of aircraft and causing flight accidents. Here, we developed a lightweight and conformable system on the wing surface of aircraft for stall sensing. Quantitative data about airflow turbulence and the degree of boundary layer separation are provided in situ using conjunct signals provided by both triboelectric and piezoelectric effects. Thus, the system can visualize and directly measure the airflow detaching process on the airfoil, and senses the degree of airflow separation during and after a stall for large aircraft and unmanned aerial vehicles.

Tactile sensors with high spatial resolution are crucial to manufacture large scale flexible electronics, and low crosstalk sensor array combined with advanced data analysis is beneficial to improve detection accuracy. Here, we demonstrated the photo-reticulated strain localization films (prslPDMS) to prepare the ultralow crosstalk sensor array, which form a micro-cage structure to reduce the pixel deformation overflow by 90.3% compared to that of conventional flexible electronics. It is worth noting that prslPDMS acts as an adhesion layer and provide spacer for pressure sensing. Hence, the sensor achieves the sufficient pressure resolution to detect 1 g weight even in bending condition, and it could monitor human pulse under different states or analyze the grasping postures. Experiments show that the sensor array acquires clear pressure imaging and ultralow crosstalk (33.41 dB) without complicated data processing, indicating that it has a broad application prospect in precise tactile detection.

There are two primary types of photoreceptor cells in the human eye: cone cells and rod cells that enable color vision and night vision, respectively. Herein, inspired by the function of human visual cells, we develop a high-resolution perovskite-based color camera using a set of narrowband red, green, blue, and broadband white perovskite photodetectors as imaging sensors. The narrowband red, green, and blue perovskite photodetectors with color perceptions mimic long-, medium-, and short-wavelength cones cells to achieve color imaging ability. Also, the broadband white perovskite photodetector with better detectivity mimics rod cells to improve weak-light imaging ability. Our perovskite-based camera, combined with predesigned pattern illumination and image reconstruction technology, is demonstrated with high-resolution color images (up to 256 × 256 pixels) in diffuse mode. This is far beyond previously reported advanced perovskite array image sensors that only work in monochrome transmission mode. This work shows a new approach to bio-inspired cameras and their great potential to strongly mimic the ability of the natural eye.

One of unsolved puzzles about water lies in how ion-water interplay affects its freezing point. Here, we report the direct link between tetrahedral entropy and the freezing behavior of water in Zn2+-based electrolytes by analyzing experimental spectra and molecular simulation results. A higher tetrahedral entropy leads to lower freezing point, and the freezing temperature is directly related to the entropy value. By tailoring the entropy of water using different anions, we develop an ultralow temperature aqueous polyaniline| |Zn battery that exhibits a high capacity (74.17 mAh g−1) at 1 A g−1 and −80 °C with ~85% capacity retention after 1200 cycles due to the high electrolyte ionic conductivity (1.12 mS cm−1). Moreover, an improved cycling life is achieved with ~100% capacity retention after 5000 cycles at −70 °C. The fabricated battery delivers appreciably enhanced performance in terms of frost resistance and stability. This work serves to provide guidance for the design of ultralow temperature aqueous batteries by precisely tuning the water structure within electrolytes.

The high-voltage power source is one of the important research directions of triboelectric nanogenerator (TENG). In this paper, a high-voltage output TENG (HVO-TENG) is proposed with direct current/alternating current (DC/AC) optimal combination method for wind energy harvesting. Through the optimal design of a direct current generation unit (DCGU) and an alternating current generation unit (ACGU), the HVO-TENG can produce DC voltage of 21.5 kV and AC voltage of 200 V, simultaneously. The HVO-TENG can continuously illuminate more than 6,000 light emitting diodes (LEDs), which is enough to drive more possible applications of TENG. Besides, this paper explored application experiments on HVO-TENG. Demonstrative experiments indicate that the high-voltage DC output is used for producing ozone, while the AC output can light up ultraviolet (UV) LEDs. The HVO-TENG can increase the ozone concentration (C) in an airtight container to 3 parts per million (ppm) after 7 h and continuously light up UV LEDs. All these demonstrations verify that the HVO-TENG has important guiding significance for designing high performance TENG.

Energy harvesting and power transmission is a significant challenge for the self-powered technologies towards mobile electronic devices. Here, we propose a hybridized energy harvester to complement each other’s strengths for simultaneously scavenging multiple types of energy and then wirelessly transmit the power. The harvester consists of electromagnetic-triboelectric nanogenerator units for collecting rotational energy and a commercial water-proof flexible solar cell. At a rotation rate of 500 rpm, the output current of electromagnetic-triboelectric nanogenerator units can reach about 630 mA through energy management. Moreover, the power harvested by hybridized energy harvester can be wirelessly transmitted up to a distance of about 100 cm in real time to charge mobile phone, anemometer, and hygrometer based on self-resonant coils. The hybridized energy harvester with wireless power transmission has potential applications in large-scale energy collection, long-distance wireless power transmission and sustainably driving mobile electronic devices.

For new renewable clean energy, triboelectric nanogenerators (TENGs) have shown great potential in response to the world energy crisis. Nevertheless, the alternating-current signal generated by a TENG needs to be converted into a direct-current signal to be effective in applications. Therefore, a power management circuit, comprising a clamp rectifier circuit and a mechanical switch, is proposed for the conversion and produces a signal having a low ripple coefficient. The power management circuit adopts a clamp circuit as the rectifier circuit to increase the rectified voltage, and reduces the loss resulted from the components by reducing the use of discrete components; the electronic switch in the buck regulator circuit is replaced with a mechanical switch to reduce cost and complexity. In a series of experiments, this power management circuit displayed a stable output voltage with a ripple voltage of 0.07 V, crest factor of 1.01, and ripple coefficient of 2.2%. The TENG provides a feasible method to generate stable electric energy and to supply power to low-consumption electronic devices.

Along with the unceasing growth of worldwide economic and the associated issues on resources, energy and environment, clean energy generating technologies that are based on recyclable materials, if possible, may become the future trend of development. Here, we report the design of a cheap, lightweight, and recyclable single-electrode triboelectric nanogenerator (TENG) that utilizes waste paper as the triboelectric material. Under the current strategy, we successfully developed green energy machines without vastly increasing the mining of various critical minerals around the world. The as-designed TENG could not only collect and convert mechanical energy into electricity with sound efficiency, but also has the merit for continuous reuse and quick construction. The maximum output power density is as high as 171 mW·m−2 at a resistance of 130 MΩ and could be integrated into a book for monitoring reading actions, thus providing a new approach to the low-cost, green and sustainable self-powered electronic systems.

Triboelectric nanogenerator (TENG) has been proved as a promising energy harvester in recent years, but the challenges of exploring economically triboelectric materials still exist and have aroused interests of many researchers. In this paper, chitosansilk fibroin-airlaid paper composite film (CSA film) was fabricated and then the CSA film based-triboelectric nanogenerator (CSA-TENG) was constructed, which presents an opportunity for natural polymers to be applied in triboelectric materials. Due to the excellent electron donating ability of CSA film, the CSA-TENG can harvest environmental energy with a high efficiency. More importantly, the as-designed CSA film based dual-electrode triboelectric nanogenerator (CSA-D-TENG) is successfully assembled into hand clapper and trampoline to harvest mechanical energies generated by human bodies, it is also capable of monitoring human movement while harvesting biomechanical energies. This work provides a simple and environmental-friendly way to develop TENG for biomechanical energies harvesting and human motion monitoring.

Biodegradable or transient electronics is an emerging technology whose key characteristic is an ability to dissolve, resorb, physically disappear or disintegrate in physiological environments after fulfilling their functions over prescribed time frames. Biodegradable electronics as temporary implants can be safely absorbed by the body, and as green electronics can effectively alleviate landfill and environmental issues caused by electronic wastes, which are expected to ultimately eliminate associated costs and risks resulting from recycling operations. In this review, the state of the art of the biodegradable polymers, their fabrication techniques, and potential applications in environment friendly electronic skins (e-skins) are comprehensively summarized and systematically discussed. In addition, the future outlook for the development of biodegradable e-skins is also discussed at the end. It is expected that this review will potentially provide vital tools and beneficial strategies for the design of biodegradable e-skins with the functions of diagnosis, therapy and green sensing that are beneficial for human healthcare and environmental protection.

Electron transfer has been proven the dominant charge carrier during contact electrification at the liquid–solid interface. However, the effect of electron spin in contact electrification remains to be investigated. This study examines the charge transfer between different liquids and ferrimagnetic solids in a magnetic field, focusing on the contribution of O2 molecules to the liquid–solid contact electrification. The findings reveal that magnetic fields promote electron transfer at the O2-containing liquid–solid interfaces. Moreover, magnetic field-induced electron transfer increases at higher O2 concentrations in the liquids and decreases at elevated temperatures. The results indicate spin-selected electron transfer at liquid–solid interface. External magnetic fields can modulate the spin conversion of the radical pairs at the O2-containing liquid and ferrimagnetic solid interfaces due to the Zeeman interaction, promoting electron transfer. A spin-selected electron transfer model for liquid–solid contact electrification is further proposed based on the radical pair mechanism, in which the HO2 molecules and the free unpaired electrons from the ferrimagnetic solids are considered radical pairs. The spin conversion of the [HO2• •e−] pairs is affected by magnetic fields, rendering the electron transfer magnetic field-sensitive.

Triboelectric polymer with high charge density is the foundation to promote the wide range of applications of triboelectric nanogenerators. This work develops a method to produce triboelectric polymer based on repeated rheological forging. The fluorinated ethylene propylene film fabricated by repeated forging method not only has excellent mechanical properties and good transmittance, but also can maintain an ultrahigh tribo-charge density. Based on the film with a thickness of 30 μm, the output charge density from contact-separation nanogenerator reaches 352 μC·m−2. Then, the same film is applied for the nanogenerator with air-breakdown mode and a charge density of 510 μC·m−2 is further achieved. The repeated forging method can effectively regulate the composition of surface functional groups, the crystallinity, and the dielectric constants of the fluorinated ethylene propylene, leading to the superior capability of triboelectrification. Finally, we summarize the key parameters for elevating the electrification performance on the basis of molecular structure and related fabrication crafts, which can guide the further development of triboelectric polymers.

Rapid development in wearable electronics has brought huge convenience to human life and gradually penetrated into various indispensable fields, such as health monitoring, medical assistance, smart sports, object tracking and smart home, etc. However, the suitable energy supply system for these wearable electronics remains an important issue to address. Fiber and textile triboelectric nanogenerators (f/t-TENGs), capable of converting biomechanical energy into electricity, have promising features to act as a mobile sustainable power source for wearable electronics or directly serve as an intelligent self-powered sensing solution. Compared with the low-output piezoelectric nanogenerators, hard-to-wear electromagnetic generators and other bulk TENGs, the fiber/textile TENG may be the best type of wearable human mechanical energy harvester at present. Herein, this review comprehensively introduces the recent progress of smart fibers and textiles with a highlight on triboelectric nanogenerators, including the general materials and structures of fiber/textile shaped electronics, various fiber and textile devices for triboelectric/triboelectric-integrated energy harvesting and self-powered smart sensing systems. Moreover, the advance of f/t-TENGs with multifunctionality and large-scale textile processing techniques is summarized as well. Finally, the challenges and perspectives of f/t-TENGs for future improvement, large-scale production and emerging applications are thoroughly discussed as well.

Textile triboelectric nanogenerator (TENG) is a kind of smart textile technology that integrates traditional flexible and wearable textile materials with emerging and advanced TENG science, which not only embraces the capabilities of autonomous energy harvesting and active self-powered sensing, but also maintains original wearability and desired comfortability. With the help of the burden-free and self-sufficient wearable intelligent system, individuals can achieve convenient acquisition and efficient utilization of electric energy, which will help to promote the future development of human-oriented on-body electronics and artificial intelligence. Here, some fundamental knowledge and core elements, including the operational modes and corresponding service occasions, charge generation and transfer mechanisms, remaining challenges and potential solutions are comprehensively summarized and systematically discussed. Based on these analyses, a roadmap toward the scientific research and large-scale commercial application of textile TENGs in the next decade is highlighted at the end of the article. We believe that textile TENGs will become an indispensable part of daily clothing in the future, thus benefiting all humankind and human civilization.

Precious metals such as gold and platinum are valued materials for a variety of important applications, but their scarcity poses a risk of supply disruption. Recycling precious metals from waste provides a promising solution; however, conventional metallurgical methods bear high environmental costs and energy consumption. Here, we report a photocatalytic process that enables one to selectively retrieve seven precious metals—silver (Ag), gold (Au), palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru) and iridium (Ir)—from waste circuit boards, ternary automotive catalysts and ores. The whole process does not involve strong acids or bases or toxic cyanide, but needs only light and photocatalysts such as titanium dioxide (TiO2). More than 99% of the targeted elements in the waste sources can be dissolved and the precious metals recovered after a simple reducing reaction that shows a high purity (≥98%). By demonstrating success at the kilogram scale and showing that the catalysts can be reused more than 100 times, we suggest that this approach might be industry compatible. This research opens up a new path in the development of sustainable technologies for recycling the Earth’s resources and contributing to a circular economy. Recovering precious resources from waste is essential to implement a circular economy, but the available methods carry environmental costs. In this Article, a greener photocatalytic process is shown to recover up to seven precious metals from waste successfully, offering the potential for wide application.

The selective catalytic oxidation of ammonia (SCO) to N2 seems to be the most promising technology to remove NH3. Compared with electrocatalytic and photocatalytic ammonia oxidation technology, the thermal catalytic oxidation ammonia technology was sufficient to support large-scale commercial and industrial applications. The NH3-SCO reaction was strongly obeyed the reaction routes of imide, hydrazinium-type and iSCR mechanism. Further, in situ (electron paramagnetic resonance) EPR spectroscopy combined with DFT calculation could provide a foundation for the design and construction of highly efficient ammonia oxidation catalyst. Finally, important ideas for NH3-SCO should be given the 100% N2 selectivity and higher NH3 conversion at lowest temperature. If Ag single-atoms were inserted in the tunnels of zeolites or MOF to result in single Ag atoms anchored at the tunnel, this single-atom Ag particles exhibited super NH3 conversion, N2 selectivity and hydrothermal durability at low temperatures.

Underwater communication is a critical and challenging issue, on account of the complex underwater environment. This study introduces an underwater wireless communication approach via Maxwell’s displacement current generated by a triboelectric nanogenerator. Underwater electric field can be generated through a wire connected to a triboelectric nanogenerator, while current signal can be inducted in an underwater receiver certain distance away. The received current signals are basically immune to disturbances from salinity, turbidity and submerged obstacles. Even after passing through a 100 m long spiral water pipe, the electric signals are not distorted in waveform. By modulating and demodulating the current signals generated by a sound driven triboelectric nanogenerator, texts and images can be transmitted in a water tank at 16 bits/s. An underwater lighting system is operated by the triboelectric nanogenerator-based voice-activated controller wirelessly. This triboelectric nanogenerator-based approach can form the basis for an alternative wireless communication in complex underwater environments.

Interface engineering by local polarization using piezoelectric1–4, pyroelectric5,6 and ferroelectric7–9 effects has attracted considerable attention as a promising approach for tunable electronics/optoelectronics, human–machine interfacing and artificial intelligence. However, this approach has mainly been applied to non-centrosymmetric semiconductors, such as wurtzite-structured ZnO and GaN, limiting its practical applications. Here we demonstrate an electronic regulation mechanism, the flexoelectronics, which is applicable to any semiconductor type, expanding flexoelectricity10–13 to conventional semiconductors such as Si, Ge and GaAs. The inner-crystal polarization potential generated by the flexoelectric field serving as a ‘gate’ can be used to modulate the metal–semiconductor interface Schottky barrier and further tune charge-carrier transport. We observe a giant flexoelectronic effect in bulk centrosymmetric semiconductors of Si, TiO2 and Nb–SrTiO3 with high strain sensitivity (>2,650), largely outperforming state-of-the-art Si-nanowire strain sensors and even piezoresistive, piezoelectric and ferroelectric nanodevices14. The effect can be used to mechanically switch the electronics in the nanoscale with fast response (

Triboelectric nanogenerator (TENG) is an emerging powerful technology for converting ambient mechanical energy into electrical energy through the effect of triboelectricity. Starting from the expanded Maxwell’s equations, the theoretical framework of TENGs has been gradually established. Here, a review is given about its recent progress in constructing of this general theory. The fundamental mechanism of TENGs is constructed by the driving force—Maxwell’s displacement current, which is essentially different from that of electromagnetic generators. Theoretical calculations of the displacement current from a three-dimensional mathematical model are presented, as well as the theoretical studies on the TENGs according to the capacitor models. Furthermore, the figure-of-merits and standards for quantifying the TENG’s output characteristics are discussed, which will provide important guidelines for optimizing the structure and performance of TENGs toward practical applications. Finally, perspectives and challenges are proposed about the basic theory of TENGs and its future technology development.

Extensive efforts have been made to harvest energy from water in the form of raindrops1–6, river and ocean waves7,8, tides9 and others10–17. However, achieving a high density of electrical power generation is challenging. Traditional hydraulic power generation mainly uses electromagnetic generators that are heavy, bulky, and become inefficient with low water supply. An alternative, the water-droplet/solid-based triboelectric nanogenerator, has so far generated peak power densities of less than one watt per square metre, owing to the limitations imposed by interfacial effects—as seen in characterizations of the charge generation and transfer that occur at solid–liquid1–4 or liquid–liquid5,18 interfaces. Here we develop a device to harvest energy from impinging water droplets by using an architecture that comprises a polytetrafluoroethylene film on an indium tin oxide substrate plus an aluminium electrode. We show that spreading of an impinged water droplet on the device bridges the originally disconnected components into a closed-loop electrical system, transforming the conventional interfacial effect into a bulk effect, and so enhancing the instantaneous power density by several orders of magnitude over equivalent devices that are limited by interfacial effects. A device involving a polytetrafluoroethylene film, an indium tin oxide substrate and an aluminium electrode allows improved electricity generation from water droplets, which bridge the previously disconnected circuit components.

Lip language is an effective method of voice-off communication in daily life for people with vocal cord lesions and laryngeal and lingual injuries without occupying the hands. Collection and interpretation of lip language is challenging. Here, we propose the concept of a novel lip-language decoding system with self-powered, low-cost, contact and flexible triboelectric sensors and a well-trained dilated recurrent neural network model based on prototype learning. The structural principle and electrical properties of the flexible sensors are measured and analysed. Lip motions for selected vowels, words, phrases, silent speech and voice speech are collected and compared. The prototype learning model reaches a test accuracy of 94.5% in training 20 classes with 100 samples each. The applications, such as identity recognition to unlock a gate, directional control of a toy car and lip-motion to speech conversion, work well and demonstrate great feasibility and potential. Our work presents a promising way to help people lacking a voice live a convenient life with barrier-free communication and boost their happiness, enriches the diversity of lip-language translation systems and will have potential value in many applications.

Polymer-based piezoelectric devices are promising for developing future wearable force sensors, nanogenerators, and implantable electronics etc. The electric signals generated by them are often assumed as solely coming from piezoelectric effect. However, triboelectric signals originated from contact electrification between the piezoelectric devices and the contacted objects can produce non-negligible interfacial electron transfer, which is often combined with the piezoelectric signal to give a triboelectric-piezoelectric hybrid output, leading to an exaggerated measured “piezoelectric” signal. Herein, a simple and effective method is proposed for quantitatively identifying and extracting the piezoelectric charge from the hybrid signal. The triboelectric and piezoelectric parts in the hybrid signal generated by a poly(vinylidene fluoride)-based device are clearly differentiated, and their force and charge characteristics in the time domain are identified. This work presents an effective method to elucidate the true piezoelectric performance in practical measurement, which is crucial for evaluating piezoelectric materials fairly and correctly.

Triboelectric nanogenerators (TENGs) can directly harvest energy via solid–liquid interface contact electrification, making them very suitable for harvesting raindrop energy and as active rainfall sensors. This technology is promising for realizing a fully self-powered system for autonomous rainfall monitoring combined with energy harvesting/sensing. Here, we report a raindrop energy-powered autonomous rainfall monitoring and wireless transmission system (R-RMS), in which a raindrop-TENG (R-TENG) array simultaneously serves as a raindrop energy harvester and rainfall sensor. At a rainfall intensity of 71 mm/min, the R-TENG array can generate an average short-circuit current, open-circuit voltage, and maximum output power of 15 μA, 1800 V, and 325 μW, respectively. The collected energy can be adjusted to act as a stable 2.5 V direct-current source for the whole system by a power management circuit. Meanwhile, the R-TENG array acts as a rainfall sensor, in which the output signal can be monitored and the measured data are wirelessly transmitted. Under a rainfall intensity of 71 mm/min, the R-RMS can be continuously powered and autonomously transmit rainfall data once every 4 min. This work has paved the way for raindrop energy-powered wireless hyetometers, which have exhibited broad prospects in unattended weather monitoring, field surveys, and the Internet of Things.

An ultra-stable all-weather service piezoelectric nanogenerator (PENG) with a wide operating temperature range (-80~80 ℃) and a wide operating relative humidity range (0~100%) is proposed. The PENG based on N doped 4H-SiC exhibits long-term service stability up to 50 days.The short circuit current density of PENG based on N doped 4H-SiC is enhanced significantly. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-021-00779-0., Ultra-stable piezoelectric nanogenerator (PENG) driven by environmental actuation sources with all-weather service capability is highly desirable. Here, the PENG based on N doped 4H-SiC nanohole arrays (NHAs) is proposed to harvest ambient energy under low/high temperature and relative humidity (RH) conditions. Finite element method simulation of N doped 4H-SiC NHAs in compression mode is developed to evaluate the relationship between nanohole diameter and piezoelectric performance. The density of short circuit current of the assembled PENG reaches 313 nA cm−2, which is 1.57 times the output of PENG based on N doped 4H-SiC nanowire arrays. The enhancement can be attributed to the existence of nanohole sidewalls in NHAs. All-weather service capability of the PENG is verified after being treated at -80/80 ℃ and 0%/100% RH for 50 days. The PENG is promising to be widely used in practice worldwide to harvest biomechanical energy and mechanical energy. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-021-00779-0.

Highlights Triboelectric nanogenerator (TENG)/carbon dots-TNs supported over three-dimensional graphene aerogel (3DGA@CDs-TNs) system was constructed.TENG and 3DGA@CDs-TNs present excellent degradation activity toward brilliant green (88.26%, 40 min) and direct blue 5B (89.6%, 90 min).The coupling interaction of photocatalysis and TENG leads to an enhanced removal ability.The degradation pathways for brilliant green and direct blue 5B are proposed. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-021-00695-3., It is of great importance to explore a creative route to improve the degradation efficiency of organic pollutants in wastewater. Herein, we construct a unique hybrid system by combining self-powered triboelectric nanogenerator (TENG) with carbon dots-TiO2 sheets doped three-dimensional graphene oxide photocatalyst (3DGA@CDs-TNs), which can significantly enhance the degradation efficiency of brilliant green (BG) and direct blue 5B (DB) owing to the powerful interaction of TENG and 3DGA@CDs-TNs photocatalyst. The power output of TENG can be applied for wastewater purification directly, which exhibits a self-powered electrocatalytic technology. Furthermore, the results also verify that TENG can replace conventional electric catalyst to remove pollutants effectively from wastewater without any consumption. Subsequently, the unstable fragments and the plausible removal pathways of the two pollutants are proposed. Our work sheds light on the development of efficient and sustainable TENG/photocatalyst system, opening up new opportunities and possibilities for comprehensive utilization of random energy. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-021-00695-3.

The rapid development of Internet of Things and artificial intelligence brings increasing attention on the harvesting of distributed energy by using triboelectric nanogenerator (TENG), especially the direct current TENG (DC-TENG). It is essential to select appropriate triboelectric materials for obtaining a high performance TENG. In this work, we provide a set of rules for selecting the triboelectric materials for DC-TENG based on several basic parameters, including surface charge density, friction coefficient, polarization, utilization rate of charges, and stability. On the basis of the selection rules, polyvinyl chloride, used widely in industry rather than in TENG, is selected as the triboelectric layer. Its effective charge density can reach up to ~8.80 mC m−2 in a microstructure-designed DC-TENG, which is a new record for all kinds of TENGs. This work can offer a basic guideline for the triboelectric materials selection and promote the practical applications of DC-TENG., Appropriate triboelectric material selection is vital to for high performance direct current triboelectric nanogenerator (DC-TENG). The authors here provide effective selection rules as guideline to select triboelectric materials for DC-TENG to reduce the trial-and-error cost for DC-TENG’s research.

Environmental deterioration, especially water pollution, is widely dispersed and could affect the quality of people’s life at large. Though the sewage treatment plants are constructed to meet the demands of cities, distributed treatment units are still in request for the supplementary of centralized purification beyond the range of plants. Electrochemical degradation can reduce organic pollution to some degree, but it has to be powered. Triboelectric nanogenerator (TENG) is a newly-invented technology for low-frequency mechanical energy harvesting. Here, by integrating a rotary TENG (R-TENG) as electric power source with an electrochemical cell containing a modified graphite felt cathode for hydrogen peroxide (H2O2) along with hydroxyl radical (•OH) generation by Fenton reaction and a platinum sheet anode for active chlorine generation, a self-powered electrochemical system (SPECS) was constructed. Under the driven of mechanical energy or wind flow, such SPECS can efficiently degrade dyes after power management in neutral condition without any O2 aeration. This work not only provides a guideline for optimizing self-powered electrochemical reaction, but also displays a strategy based on the conversion from distributed mechanical energy to chemical energy for environmental remediation.

Aybrid tribo/piezoelectric nanogenerators (HTPENG) have been proven to be highly efficient and versatile as far as the collection and conversion of ambient energy are concerned, and the introduction of flexible and green materials is a key step for their potential applications. Here, we developed a HTPENG by using nitrocellulose nanofibril paper as the triboelectric layer and BaTiO3/MWCNT@bacterial cellulose paper as the piezoelectric layer. The output of the triboelelctric paper has considerable performance as fluorinated ethylene propylene, and the output of piezoelectric paper is more than ten times higher than the BTO/polydimethylsiloxane structure. The integrated outputs of the sandwich structured HTPENG are 18 V and 1.6 µA·cm−2, which are capable of lighting up three LED bulbs and charging a 1 µF capacitor to 2.5 V in 80 s. In addition, the voltage signal generated by the HTPENG in contact-separation mode can be used for dynamic pressure detection. The linear range of dynamic pressure is from 0.5 to 3 N·cm−2 with a high sensitivity of 8.276 V·cm2 N−1 and a detection limit of 0.2 N·cm−2. This work provides new insights into the design and application of cellulose-based hybrid nanogenerators with high flexibility and simple structure.

As a new-era of energy harvesting technology, the enhancement of triboelectric charge density of triboelectric nanogenerator (TENG) is always crucial for its large-scale application on Internet of Things (IoTs) and artificial intelligence (AI). Here, a microstructure-designed direct-current TENG (MDC-TENG) with rationally patterned electrode structure is presented to enhance its effective surface charge density by increasing the efficiency of contact electrification. Thus, the MDC-TENG achieves a record high charge density of ~5.4 mC m−2, which is over 2-fold the state-of-art of AC-TENGs and over 10-fold compared to previous DC-TENGs. The MDC-TENG realizes both the miniaturized device and high output performance. Meanwhile, its effective charge density can be further improved as the device size increases. Our work not only provides a miniaturization strategy of TENG for the application in IoTs and AI as energy supply or self-powered sensor, but also presents a paradigm shift for large-scale energy harvesting by TENGs., Low charge density is the bottleneck for the applications of triboelectric nanogenerator (TENG). Here, the authors demonstrate a microstructure-designed direct-current TENG with rationally patterned electrode structure to enhance its effective charge density to a new milestone.

As an emerging technology for harvesting mechanical energy, low surface charge density greatly hinders the practical applications of triboelectric nanogenerators (TENGs). Here, a high-performance TENG based on charge shuttling is demonstrated. Unlike conventional TENGs with static charges fully constrained on the dielectric surface, the device works based on the shuttling of charges corralled in conduction domains. Driven by the interaction of two quasi-symmetrical domains, shuttling of two mirror charge carriers can be achieved to double the charge output. Based on the mechanism, an ultrahigh projected charge density of 1.85 mC m−2 is obtained in ambient conditions. An integrated device for water wave energy harvesting is also presented, confirming its feasibility for practical applications. The device provides insights into new modes of TENGs using unfixed charges in domains, shedding a new light on high-performance mechanical energy harvesting technology., Conventionally, triboelectric nanogenerators are based on static charges fixed on dielectric surfaces. Here, the authors report a new mechanism using shuttling of mirror charge carriers corralled in quasi-symmetrical conduction domains, which boosts performance for blue energy harvesting.

Owing to the advantages of integration and being magnet-free and light-weight, the switched-capacitor-convertor plays an increasing role compared to traditional transformer in some specific power supply systems. However, the high output impedance and switching loss largely reduces its power efficiency, due to imperfect topology and transistors. Herein, we propose a fractal-design based switched-capacitor-convertors with characteristics including high conversion efficiency, minimum output impedance, and electrostatic voltage applicability. As a double-function output power management system for triboelectric nanogenerators, it delivers over 67 times charge boosting and 954 W m−2 power density in pulse mode, and achieves over 94% total energy transfer efficiency in constant mode. The establishment of the fractal-design switched-capacitor-convertors provides significant guidance for the development of power management toward multi-functional output for numerous applications. The successful demonstration in triboelectric nanogenerators also declares its great potential in electric vehicles, DC micro-grids etc., Power management systems are urgently needed for maximally utilizing the energy generated from triboelectric energy devices. Here, the authors report a fractal-designed switched-capacitor-convertor as a high efficiency power management strategy for triboelectric nanogenerators.