Search

Triboelectric nanogenerators (TENGs) can collect and convert random mechanical energy into electric energy, with remarkable advantages including broadly available materials, straightforward preparation, and multiple applications. Over the years, researchers have made substantial advancements in the theoretical and practical aspects of TENG. Nevertheless, the pivotal challenge in realizing full applications of TENG lies in ensuring that the generated output meets the specific application requirements. Consequently, substantial research is dedicated to exploring methods and mechanisms for enhancing the output performance of TENG devices. This review aims to comprehensively examine the influencing factors and corresponding improvement strategies of the output performance based on the contact electrification mechanism and operational principles that underlie TENG technology. This review primarily delves into five key areas of improvement: materials selection, surface modification, component adjustments, structural optimization, and electrode enhancements. These aspects are crucial in tailoring TENG devices to meet the desired performance metrics for various applications. [ABSTRACT FROM AUTHOR]

Wearable sensors for high temperatures (WSHT) applications pose a significant challenge in the electronics field due to the inherent inability of most electronics to function in harsh environments. Triboelectric nanogenerators (TENG) present a substantial potential for applications in such challenging conditions. Herein, a fully‐recyclable flame‐retardant triboelectric elastomer is developed, which exhibits superior charge stability under high temperature conditions and proposes the specially designed synergistic fillers that play a dual role by trapping more charges into the interface and stabilizing the char layers via layer‐ball‐layer structure. An efficient flame‐retardant system is presented, which exhibits a 31% lower fire growth index than the individual components. The maximum surface charge density of this triboelectric elastomer can reach 361 µC m−2, while this surface charge density can be preserved to 70.9% after 16 s of combustion (≈520 °C) and to 37.9% by continuously working at 130 °C. At last, utilizing this flame‐retardant triboelectric elastomer, smart firemen's boots featuring gait analysis for identification and second level early warning systems have been developed. This work paves the way for the development of triboelectric materials and intelligent wearable devices suitable for applications in harsh environments. [ABSTRACT FROM AUTHOR]

The rapid development of the Internet of Things has led to numerous functional electronic devices, making it a significant challenge to provide power for these distributed devices. Triboelectric self‐power technology is ideal for smart devices due to its material diversity and high energy efficiency. However, traditional triboelectric materials have weak electrostatic induction due to their low dielectric constant. Additionally, the thermionic emission effect reduces their electric output in high temperatures, limiting their applications. This study designes a thermally robust aramid triboelectric material with a high dielectric constant through heat‐induced cross‐linking heterogeneous interface engineering. This novel material not only achieves high triboelectric output but also maintains high performance across a wide temperature range. The heat‐induced cross‐linking process enhances the interaction between aramid nanofibers and Al2O3 nanosheets, significantly improving the electrical performance, and flame retardance of the material, and the relative dielectric constant increases 16‐fold. The triboelectric nanogenerator constructed with this material achieves a power density of 3.97 W m−2, and maintains high triboelectric output at 260 °C. Finally, a self‐powered detection system collects high‐temperature gas energy and drives sensors is designed. This research presents a novel strategy for high‐performance triboelectric materials, showing significant potential for self‐powered devices. [ABSTRACT FROM AUTHOR]

The seamless integration of advanced triboelectric nanogenerators with fiber material has propelled the rapid advancement of intelligent wearable electronics. The overheating and mechanical abrasion associated with prolonged operation poses a significant challenge for conventional fiber‐based triboelectric materials. Aramid fibers, characterized by high thermal stability, ultra‐high mechanical strength, and excellent insulating properties, can effectively compensate for the limitations of triboelectric materials. However, the intrinsic advantages of aramid fiber triboelectric materials and their general structural design strategies have not yet to be comprehensively elucidated. In this review, the synthesis methods and development history of aramid fiber triboelectric materials in recent years are summarized. Importantly, the unique advantages and development potential of aramid fibers as triboelectric materials are systematically discussed, particularly regarding high‐temperature resistance, high strength, and electrical insulation. Furthermore, the latest advancements in the structural design and performance modulation of aramid fiber triboelectric materials are presented. The aramid fiber‐based self‐powered wearable electronics in high‐temperature warning, impact monitoring, and human energy harvesting are summarized. Finally, the challenges and opportunities facing the future development of aramid fiber‐based triboelectric nanogenerators are discussed. [ABSTRACT FROM AUTHOR]

Self‐healing materials that integrate excellent mechanical properties and high healing efficiency meet the requirements of flexible electronic sensors for mechanical flexibility and reliability. In the field of wearable devices, they are of great significance for improving the stability of the equipment and reducing the frequency of replacement. However, the high strength of materials often limits their self‐healing ability. When damage occurs, it will hinder the microstructural adjustment and fluidity of the material at the damaged site, thus negatively affecting the activation and execution of the self‐healing mechanism. In this study, a strength‐toughness and room‐temperature self‐healing triboelectric material is prepared by the dynamic nanoconfinement effect and the quenching effect of ethanol (referred to as the DNCQ strategy). The quenching effect of ethanol improves the aggregation of nanocluster phase, and the constructed nanoconfined network skillfully balances the contradiction between mechanical properties and self‐healing ability. The obtained triboelectric material has high tensile strength (27.1 MPa), toughness (97.9 MJ m−3), and excellent healing efficiency (88.6%). The self‐powered pressure distribution sensing array based on triboelectric materials can accurately reflect the pressure distribution of the object, which has potential application prospects in the field of wearable devices. [ABSTRACT FROM AUTHOR]

The rapid development of wearable electronics has placed higher demands on the design strategies of triboelectric materials. Aerogels have the potential to become advanced triboelectric materials, however, traditional design strategies often require complex processes and additional chemical cross‐linking agents to improve the stability of the gel structure, which limits its practical application. In this work, a scalable and sustainable self‐assembly drive strategy is proposed for the design of bio‐based triboelectric aerogels with multi‐scale winding structures. Interestingly, the autoacceleration effect, which is regarded as "unfavorable" during the autocatalytic polymerization of supramolecules, is rationally exploited to provide the supramolecules within the matrix with an abundance of multiple hydrogen bonds at the same time as their rapid gelation occurs. Thanks to this, the aerogel film exhibits ultra‐high tensile strength (104 MPa) and remains undeformed after resisting an impact of 8000 times its own weight. Highly robust triboelectric aerogel films are used to build wearable self‐powered sensors with ultra‐fast response in complex environments (48 ms), while enabling real‐time interaction between the wearer and the information network. The design idea of " turning a detriment into an asset " in this work provides a new idea for the material construction of highly robust wearable sensors. [ABSTRACT FROM AUTHOR]

Highlights Typical structures/working mechanisms of gel-based triboelectric nanogenerators and performance advantages of gel materials reviewed. Optimization of hydrogels, organogels, and aerogels for triboelectric nanogenerators in flexible sensing summarized. Applications, challenges, and future development directions of gel-based triboelectric nanogenerators in flexible sensing are discussed.

Highlights: Typical structures/working mechanisms of gel-based triboelectric nanogenerators and performance advantages of gel materials reviewed. Optimization of hydrogels, organogels, and aerogels for triboelectric nanogenerators in flexible sensing summarized. Applications, challenges, and future development directions of gel-based triboelectric nanogenerators in flexible sensing are discussed. The rapid development of the Internet of Things and artificial intelligence technologies has increased the need for wearable, portable, and self-powered flexible sensing devices. Triboelectric nanogenerators (TENGs) based on gel materials (with excellent conductivity, mechanical tunability, environmental adaptability, and biocompatibility) are considered an advanced approach for developing a new generation of flexible sensors. This review comprehensively summarizes the recent advances in gel-based TENGs for flexible sensors, covering their principles, properties, and applications. Based on the development requirements for flexible sensors, the working mechanism of gel-based TENGs and the characteristic advantages of gels are introduced. Design strategies for the performance optimization of hydrogel-, organogel-, and aerogel-based TENGs are systematically summarized. In addition, the applications of gel-based TENGs in human motion sensing, tactile sensing, health monitoring, environmental monitoring, human–machine interaction, and other related fields are summarized. Finally, the challenges of gel-based TENGs for flexible sensing are discussed, and feasible strategies are proposed to guide future research. [ABSTRACT FROM AUTHOR]

Mechanical equipment is ubiquitous in industrial production, and the vibration energy generated by its operation usually cannot be effectively harvested, resulting in huge energy waste. Meanwhile, real‐time monitoring of machine operation can be achieved by collecting vibration information. Indeed, vibration energy harvesting and vibration monitoring are of great significance for the development of green energy and machine fault diagnosis. As an emerging power generation technology, triboelectric nanogenerator (TENG) has shown extraordinary potential in the field of vibration energy harvesting and vibration monitoring. First, the theoretical basis, working modes, and triboelectric materials are described. Then, TENG devices for vibration energy harvesting are classified and introduced based on the structural characteristics, and the main advantages and disadvantages are compared. Furthermore, the current research progress of a self‐powered vibration monitoring system based on TENG is introduced. Finally, the shortcomings of triboelectric nanogenerators in this field are analyzed and summarized, and future research directions and application scenarios are prospected. [ABSTRACT FROM AUTHOR]

The advent of self‐powered wearable electronics will revolutionize the fields of smart healthcare and sports monitoring. This technological advancement necessitates more stringent design requirements for triboelectric materials. The triboelectric aerogels must enhance their mechanical properties to address the issue of structural collapse in real‐world applications. This study fabricates stiff nanocellulosic triboelectric aerogels with multiscale structures induced by the Hofmeister effect. The aggregation and crystallization of polymer molecular chains are enhanced by the Hofmeister effect, while ice crystal growth imparts a porous structure to the aerogel at the micron scale. Therefore, the triboelectric aerogel exhibits exceptional stiffness, boasting a Young's modulus of up to 142.9 MPa and a specific modulus of up to 340.6 kN m kg–1, while remaining undeformed even after supporting 6600 times its weight. Even after withstanding an impact of 343 kPa, highly robust wearable self‐powered sensors fabricated with triboelectric aerogels remain operational. Additionally, the self‐powered sensor is capable of accurately detecting human movements, particularly in abnormal fall postures detection. This study provides considerable research and practical value for promoting material design and broadening application scenarios for self‐powered wearable electronics. [ABSTRACT FROM AUTHOR]

Highlights This review systematically discusses the interfacial properties of cellulosic material preparation processes, top-down, bottom-up, and composite processes. The rational design strategies of cellulosic triboelectric materials are summarized in detail, and the effects of different design strategies on the surface charge characteristics and charge density of cellulosic triboelectric materials are discussed. A comprehensive review of the research progress of cellulosic triboelectric nanogenerators in the field of self-powered wearable electronics.

[Display omitted] Triboelectric nanogenerators (TENGs), as a new energy conversion device in self-powered sensing devices, have been used at extreme environmental conditions, which poses great challenges to the structural stability and chemical tolerance of triboelectric materials. However, the low tolerance characteristics of traditional triboelectric materials limit their expansion in emerging applications. Cellulose, with its unique multidimensional structure and, controlled surface chemistry regulation advantages, shows great potential in resisting extreme environmental conditions and is emerging as a new candidate. This review aims to design and fabricate cellulosic triboelectric materials with exceptional tolerance, providing a perspective on the emerging applications of TENGs at extreme environmental conditions. First, the performance advantages and design principles of action of cellulosic triboelectric materials at extreme environmental conditions are described. Second, the importance of physical and chemical regulation strategies is discussed through the multi-scale perspective from macroscopic fiber bundles to microscopic cellulose molecules. It also presents the latest applications of cellulosic triboelectric materials at extreme environmental conditions such as wide temperature, high humidity, high corrosion, and radiation. Finally, the idea of how cellulosic triboelectric materials can further expand the development of TENGs application areas is presented. [ABSTRACT FROM AUTHOR]

The rapid rise of triboelectric nanogenerators (TENGs), which are emerging energy conversion devices in advanced electronics and wearable sensing systems, has elevated the interest in high‐performance and multifunctional triboelectric materials. Among them, cellulosic materials, affording high efficiency, biodegradability, and customizability, are becoming a new front‐runner. The inherently low dielectric constant limits the increase in the surface charge density. However, owing to its unique structure and excellent processability, cellulose shows great potential for dielectric modulation, providing a strong impetus for its advanced applications in the era of Internet of Things and artificial intelligence. This review aims to provide comprehensive insights into the fabrication of dielectric‐enhanced cellulosic triboelectric materials via dielectric modulation. The exceptional advantages and research progress in cellulosic materials are highlighted. The effects of the dielectric constant, polarization, and percolation threshold on the charge density are systematically investigated, providing a theoretical basis for cellulose dielectric modulation. Typical dielectric characterization methods are introduced, and their technical characteristics are analyzed. Furthermore, the performance enhancements of cellulosic triboelectric materials endowed by dielectric modulation, including more efficient energy harvesting, high‐performance wearable electronics, and impedance matching via material strategies, are introduced. Finally, the challenges and future opportunities for cellulose dielectric modulation are summarized. [ABSTRACT FROM AUTHOR]

Highlights: This review systematically discusses the interfacial properties of cellulosic material preparation processes, top-down, bottom-up, and composite processes. The rational design strategies of cellulosic triboelectric materials are summarized in detail, and the effects of different design strategies on the surface charge characteristics and charge density of cellulosic triboelectric materials are discussed. A comprehensive review of the research progress of cellulosic triboelectric nanogenerators in the field of self-powered wearable electronics. With the rapid development of the Internet of Things and flexible electronic technologies, there is a growing demand for wireless, sustainable, multifunctional, and independently operating self-powered wearable devices. Nevertheless, structural flexibility, long operating time, and wearing comfort have become key requirements for the widespread adoption of wearable electronics. Triboelectric nanogenerators as a distributed energy harvesting technology have great potential for application development in wearable sensing. Compared with rigid electronics, cellulosic self-powered wearable electronics have significant advantages in terms of flexibility, breathability, and functionality. In this paper, the research progress of advanced cellulosic triboelectric materials for self-powered wearable electronics is reviewed. The interfacial characteristics of cellulose are introduced from the top-down, bottom-up, and interfacial characteristics of the composite material preparation process. Meanwhile, the modulation strategies of triboelectric properties of cellulosic triboelectric materials are presented. Furthermore, the design strategies of triboelectric materials such as surface functionalization, interfacial structure design, and vacuum-assisted self-assembly are systematically discussed. In particular, cellulosic self-powered wearable electronics in the fields of human energy harvesting, tactile sensing, health monitoring, human–machine interaction, and intelligent fire warning are outlined in detail. Finally, the current challenges and future development directions of cellulosic triboelectric materials for self-powered wearable electronics are discussed. [ABSTRACT FROM AUTHOR]

Abstract The rapid rise of triboelectric nanogenerators (TENGs), which are emerging energy conversion devices in advanced electronics and wearable sensing systems, has elevated the interest in high‐performance and multifunctional triboelectric materials. Among them, cellulosic materials, affording high efficiency, biodegradability, and customizability, are becoming a new front‐runner. The inherently low dielectric constant limits the increase in the surface charge density. However, owing to its unique structure and excellent processability, cellulose shows great potential for dielectric modulation, providing a strong impetus for its advanced applications in the era of Internet of Things and artificial intelligence. This review aims to provide comprehensive insights into the fabrication of dielectric‐enhanced cellulosic triboelectric materials via dielectric modulation. The exceptional advantages and research progress in cellulosic materials are highlighted. The effects of the dielectric constant, polarization, and percolation threshold on the charge density are systematically investigated, providing a theoretical basis for cellulose dielectric modulation. Typical dielectric characterization methods are introduced, and their technical characteristics are analyzed. Furthermore, the performance enhancements of cellulosic triboelectric materials endowed by dielectric modulation, including more efficient energy harvesting, high‐performance wearable electronics, and impedance matching via material strategies, are introduced. Finally, the challenges and future opportunities for cellulose dielectric modulation are summarized.

The properties of materials play a significant role in triboelectric nanogenerators (TENGs). Advanced triboelectric materials for TENGs have attracted tremendous attention because of their superior advantages (e.g., high specific surface area, high porosity, and customizable macrostructure). These advanced materials can be extensively applied in numerous fields, including energy harvester, wearable electronics, filtration, and self‐powered sensors. Hence, designing triboelectric materials as advanced functional materials is important for the development of TENGs. Herein, the structural modification methods based on electrospinning to improve the triboelectric properties and the latest research progress in this kind of TENGs are systematically summarized. Preparation methods and design trends of nanofibers, microspheres, hierarchical structures, and doping nanomaterials are highlighted. The factors influencing the formation and properties of triboelectric materials are considered. Furthermore, the latest progress on the applications of TENGs is systematically elaborated. Finally, the challenges in the development of triboelectric materials are discussed, thereby guiding researchers in the large‐scale application of TENGs. [ABSTRACT FROM AUTHOR]

With the vigorous development of the Internet of Things and artificial intelligence, the active sensing system based on triboelectric nanogenerators plays an excellent performance potential and application value as a pioneering technology for smart manufacturing. Nevertheless, achieving material innovation to strike a good balance between active sensing systems and environmental friendliness remains a difficult task. As the most abundant biopolymer on earth, the sustainability potential and excellent performance of cellulose are of great importance for the development of smart sensing systems. This review intends to provide a new perspective on the sustainability of smart active sensing systems to design and fabricate cellulosic triboelectric materials for self‐powered sensing systems. Herein, the structure and advantageous properties of cellulosic triboelectric materials are briefly described. Furthermore, the structure–property–application relationship of the materials is addressed from the perspective of material design and structure optimization. Next, the latest applications of cellulose triboelectric materials are comprehensively described in smart sensing fields such as environmental monitoring, smart home, smart medical, human–machine interaction, and the Internet of everything. Lastly, the current challenges and future developments of cellulose triboelectric materials for smart sensor systems are presented. [ABSTRACT FROM AUTHOR]

In the new energy era, triboelectric nanogenerator (TENG) effectively converts weak water energy into electricity to drive sensors and electronic components, which has a very broad research prospect. However, the functional materials of TENG are usually insulating, resulting in low-current and high-resistance problems. Guided by Wang's electrical double layer model, we demonstrate that tungsten presents excellent electricity generation performance in flowing water due to its unique defect structure as evidenced by comparing the electricity generation of tungsten, tantalum, titanium, and copper, and testing their electrochemical impedance spectroscopy and X-ray diffraction characteristics. Hence, the study proposes a novel tungsten-liquid TENG for water-flowing energy harvesting, which has outstanding advantages of high DC density, low internal resistance, simple structure, and no complex electrical power required. A tungsten-liquid TENG continuously outputs 3∼20μA in 0.1–2.0M NaCl liquids at a flow rate of 400 mL/min, with output current densities up to 230 mA/m2 and internal resistances down to 6.4–67 kΩ. Ten-tungsten-liquid TENG outputs nearly 40μA, and multiple tungsten electrodes in parallel can effectively enhance the current. Notably, the study is not only beneficial for capturing the current energy in oceans with high-ionic concentrations, but also broadens the research ideas of TENG for promoting the selection of novel functional materials. [Display omitted] • The study proposes a novel tungsten-liquid TENG for water-flowing energy harvesting. • Tungsten-liquid TENG can continuously outputs 3∼20μA in 0.1-2.0M NaCl liquids (400 mL/min), with output current densities up to 230mA/m2 and internal resistances down to 6.4-67kΩ. • Demonstrate that tungsten presents excellent electricity generation performance in flowing water due to its unique defect structure as evidenced by XRD characteristics. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENGs) as an avant-garde technology that transforms mechanical energy into electrical energy, offering a new direction for green energy and sustainable development. By means of high-efficiency TENGs, conventional materials as new triboelectric materials have exhibited multi-attribute characteristics, achieving innovative applications in the field of micro-nano energy harvesting and self-powered sensing. The progress of TENGs technology with the triboelectric materials is complementary and mutually promoting. On the one hand, one of the cruxes of TENGs lies in the triboelectric materials, which have a decisive impact on their performance. On the other hand, as the research and application of TENGs continue to deepen, higher demands are placed on triboelectric materials, which in turn promotes the advancement of the entire material system as well as the fields of materials science and physics. This work aims to delve into the characteristics, types, preferred choices, and modification treatments of triboelectric materials on the performances of TENGs, hoping to provide guidance and insights for future research and applications., (© 2024 Wiley‐VCH GmbH.)

Against the backdrop of rapid advancements in 5G and Internet of Things (IoT) technologies, there is an urgent need to upgrade food sensing systems to achieve automation, digitalization, and intelligence. However, this transformation process faces numerous challenges. Triboelectric nanogenerators (TENGs), as an emerging energy conversion and sensing technology, play a crucial role in this context. They not only provide power to functional devices but also serve as sensors in multifunctional self-powered food sensing systems, capable of detecting various physical and chemical information. This review explores the development of TENGs in the field of food sensing, focusing on the working principles of their self-powered sensing. The review also systematically organizes and classifies the material and device designs used for TENGs in various food applications. Based on the performance of TENGs, a detailed introduction is provided on the specific applications of self-powered food sterilization, self-powered food quality monitoring, and self-powered taste sensing in the field of food safety. Finally, this paper discusses the challenges and corresponding strategies of TENGs in the food sensing field. The aim is to further promote unmanned and smart services and management in the food sector and to provide new research perspectives., (© 2024 Wiley‐VCH GmbH.)

The surge in interest for wearable electronics has sparked a significant demand for self-powered sensors. This necessitates the development of triboelectric materials that align with the requirements of self-powered sensors for high stability, efficiency, and broad application. Herein, we developed a single-electrode triboelectric sensor (SE-PFCPS) utilizing porous F-CNW/PDMS composite films. The SE-PFCPS demonstrated impressive output performance (V OC of 189.70 V, I SC of 0.88 μA and Q SC of 42.81 μC/m2), while retaining this high level of performance consistently over 12,000 repetitive contact separation motions. Notably, the SE-PFCPS proves its versatility by accurately monitoring human joint flexion, including the palms, wrists, elbows, and knees, as well as human walking, without the need for additional power sources. In addition, the SE-PFCPS's utility extends to tactile sensing applications, enabling functionalities such as direct writing intelligence and the composition of messages in Morse code. The sensor stands out for its stability, efficiency, and applicability across various fields, offering promising prospects for innovations in areas such as digital writing without paper or pens, monitoring of writing habits, and cryptographic transmission of information. [Display omitted] • Introduction of fluorine based on self-assembly of PFDTES on CNW surface. • Porous F-CNW/PDMS films have enhanced friction electrical output. • The SE-PFCPS features stable and accurate sensing. [ABSTRACT FROM AUTHOR]

Owing to their low cost, customizability, and environmental stability, cellulosic triboelectric materials have emerged among polymer materials. However, the rich hydrogen bonding network inherent in cellulose limits its polarity and electron-donating ability, and charge dissipation caused by the hygroscopicity of the hydroxyl-rich groups limits its application as a triboelectric material. In this study, a more convenient, economical, and environmentally friendly "stent surgery" strategy was adopted. The wetting and swelling of fiber molecules allowed Cu (II) coordination with hydroxyl groups in nanocellulose. The coordination effect of cellulose hydroxyl groups weakens the intermolecular hydrogen bonding network, leading to an increase in the molecular dipole moment and the formation of new polar regions to regulate its space charge distribution, which significantly improved the electron-supplying capacity of the nanocellulose materials, and the maximum output power density increased by a factor of 2.78 (from 45 to 125 μW cm−2). Notably, the CNF-Cu (II) triboelectric material demonstrated excellent antimicrobial (>99%) and UV transmittance (<8%) as well as resistance to humidity interference, exhibiting only 5.9% voltage output loss at high humidity (90% RH). The design of this study provides new approaches for cellulose polarity modulation and energy harvesting adapted to harsh environments. [Display omitted] • Incorporating Cu (II) increases the molecular spacing of cellulose, modulating hydrogen bonding network. • The cellulose hydroxyl coordination effect with Cu (II) modulates its molecular dipole moment and space charge distribution. • Cellulose nanofibers (CNF) incorporating Cu (II) demonstrated enhanced triboelectric performance. • The CNF-Cu (II) film showed excellent antimicrobialenhanced adaptability to high-humidity environments. [ABSTRACT FROM AUTHOR]

[Display omitted] 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. [ABSTRACT FROM AUTHOR]

Wearable sensors are experiencing vibrant growth in the fields of health monitoring systems and human motion detection, with comfort becoming a significant research direction for wearable sensing devices. However, the weak moisture-wicking capability of sensor materials leads to liquid retention, severely restricting the comfort of the wearable sensors. This study employs a pattern-guided alignment strategy to construct microhill arrays, endowing triboelectric materials with directional moisture-wicking capability. Within 2.25 s, triboelectric materials can quickly and directionally remove the droplets, driven by the Laplace pressure differences and the wettability gradient. The directional moisture-wicking triboelectric materials exhibit excellent pressure sensing performance, enabling rapid response/recovery (29.1/37.0 ms), thereby achieving real-time online monitoring of human respiration and movement states. This work addresses the long-standing challenge of insufficient moisture-wicking driving force in flexible electronic sensing materials, holding significant implications for enhancing the comfort and application potential of electronic skin and wearable electronic devices.

Copyright of Transactions of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Triboelectric nanogenerator (TENG) manifests distinct advantages such as multiple structural selectivity, diverse selection of materials, environmental adaptability, low cost, and remarkable conversion efficiency, which becomes a promising technology for micro-nano energy harvesting and self-powered sensing. Tribo-dielectric materials are the fundamental and core components for high-performance TENGs. In particular, the charge generation, dissipation, storage, migration of the dielectrics, and dynamic equilibrium behaviors determine the overall performance. Herein, a comprehensive summary is presented to elucidate the dielectric charge transport mechanism and tribo-dielectric material modification principle toward high-performance TENGs. The contact electrification and charge transport mechanism of dielectric materials is started first, followed by introducing the basic principle and dielectric materials of TENGs. Subsequently, modification mechanisms and strategies for high-performance tribo-dielectric materials are highlighted regarding physical/chemical, surface/bulk, dielectric coupling, and structure optimization. Furthermore, representative applications of dielectric materials based TENGs as power sources, self-powered sensors are demonstrated. The existing challenges and promising potential opportunities for advanced tribo-dielectric materials are outlined, guiding the design, fabrication, and applications of tribo-dielectric materials., (© 2024 Wiley‐VCH GmbH.)

The rapid growth in energy consumption demands has spurred new requirements for energy harvesting technologies. Among these, the triboelectric nanogenerator (TENG) stands out as a promising sustainable energy collection device, garnering increasing attention for its efficient conversion of mechanical energy into electrical energy. This surge in interest has further fueled exploration into novel materials and fabrication techniques. In recent years, liquid metal (LM) with unique fluidity and conductivity has been developed as a triboelectric material. Liquid metal-based TENGs (LM-TENGs) possess remarkable advantages in terms of conductivity, flexibility, high stability, and functionality, demonstrating immense potential in performance. Herein, the latest progress of LM-based triboelectric materials and their TENGs are systematically summarized. Firstly, the development, characteristics, principles of improving TENGs performance, and design methods of LM-based triboelectric materials are introduced. Meanwhile, the design methods of LM-TENGs are comprehensively investigated, such as patterning, encapsulating, and blending. The applications and trends of LM-TENGs in energy harvesting, electronic textiles, electronic skins, and self-powered sensors are introduced in detail. Finally, key issues and challenges in this field are discussed, along with prospects for future development. [Display omitted] • The design methods and advantages of liquid metal-based triboelectric materials are summarized. • The progress of energy harvesting, wearables, and self-powered sensors using liquid metal-based TENG is introduced. • Suggestions for trends of design methods and applications in liquid metal-based TENG are proposed. [ABSTRACT FROM AUTHOR]

The growing need for alternative sources to power Internet of Things and autonomous devices has led to many energy harvesting solutions from ambient energy sources. Use of batteries requires complementary energy source for extending the lifetime of the device. In recent times, triboelectric nanogenerators have gained significant attention in charging applications through ambient energy harvesting field due to their simplicity, efficiency and adaptability to many device configurations in nature. It is deemed to sustainably address power for autonomous smart applications in various environmental conditions. In this work, a state-of-the-art triboelectric nanogenerator based on wind actuated venturi design system is demonstrated in sync with the smart system evolution for powering various sensor nodal network. Using natural wind, the 3D printed wind actuated venturi triboelectric energy harvester converts ambient mechanical energy into electricity. This simple and compact device produces an optimum average power of 1.5 mW and produces a maximum output power density of 2850 mW m−2 (peak power output of 4.5 mW), which is much higher than the existing reports that use larger surface area at higher wind velocity. Extensive material testing and future implementation in an array of applications aid for environment friendly energy production and increase the role of triboelectric nanogenerator in autonomous applications. Image 1 • A compact and high performance wind actuated venturi triboelectric energy harvester is demonstrated and shows enhanced output power density of 2850 mW m−2. • The study on relation between the venturi throat gap spacing and the charge transfer leading to the conceptualization of an optimized device at low wind speeds. • A Polycarbonate (PC) flag film is employed to overcome issues related to long term reliability in complex wind environment. • Device sizing not only amplifies the output performance but also addresses to various environmental applications with an efficient charging to a storage device. [ABSTRACT FROM AUTHOR]

Abstract: To meet future needs for clean and sustainable energy, tremendous progress has been achieved in development for scavenging wind energy. The most classical approach is to use the electromagnetic effect based wind turbine with a diameter of larger than 50 m and a weight of larger than 50 ton, and each of them could cost more than $0.5 M, which can only be installed in remote areas. Alternatively, triboelectric nanogenerators based on coupling of contact‐electrification and electrostatic induction effects have been utilized to scavenge wind energy, which takes the advantages of high voltage, low cost, and small size. Here, the development of a wind‐driven triboelectric nanogenerator by focusing on triboelectric materials optimization, structure improvement, and hybridization with other types of energy harvesting techniques is reviewed. Moreover, the major applications are summarized and the challenges that are needed to be addressed and development direction for scavenging wind energy in future are highlighted. [ABSTRACT FROM AUTHOR]

The pervasive wearable electronic devices are driving sensor innovation towards increased diversity and multifunctionality, to meet the needs of complex and varied environments. The accuracy of wearable sensors in detecting and feedback on stress is typically contingent upon the responsiveness of material structures, which can be easily perturbed by environmental humidity. In this study, one with excellent hydrophobicity and moisture resistance was developed, thereby effectively suppressing the electrostatic shielding effect caused by water ionization, while retaining the inherent ability of the material surface to generate and capture charges. In high-humidity environments (98 % RH), the self-powered sensor exhibited a full scale output retention rate of over 82.4 %, thus overcoming the limitations of sensor application in such conditions. This study provides new insight into high-performance sensing that is resistant to environmental interference, which is of great significance for the development and design of electronic skin, wearable electronic devices, and soft robotics. [Display omitted] • Air humidity is an unavoidable environmental disturbance for sensors. • Hydrophobicity of the material enhances sensing stability in wet environments. • Surface microstructure enhances both hydrophobic and sensing properties. • Over 84.2 % charge retention of materials in high humidity environments. [ABSTRACT FROM AUTHOR]

The efficient energy harvesting from the environment provides a sustainable solution to alleviate the growing global energy crisis. However, the development of energy harvesting is limited by the challenge of maintaining stability under harsh atmospheric conditions. In this study, a novel chitosan/di-aldehyde nanocrystalline cellulose bio-based triboelectric material (CDTM) was constructed by a combined process of casting and hot pressing and applied to energy harvesting under harsh atmospheric conditions such as high temperature and high humidity. Chitosan and di-aldehyde nanocellulose were tightly bound by the Schiff base reaction, which strengthened the internal binding of CDTM making it more stable. More importantly, the CDTM based triboelectric nanogenerators (CD-TENGs) had an open circuit voltage retention of five times higher than that of paper at 99 RH% and could still retain 98% at a high-temperature environment, demonstrating excellent resistance to environmental disturbances. In addition, the CD-TENG was used as a wireless sensing terminal for smart devices to enable wireless visual sensing for stress intensity feedback and motion state detection. This work provides a novel insight into the design and preparation of triboelectric materials that withstand harsh atmospheric conditions. [Display omitted] • A cellulosic triboelectric material with stable surface charge density under high humidity and hot environments was prepared. • It shows excellent resistance to environmental disturbances. • It was employed as a wireless sensing terminal for smart devices, enabling wireless visual sensing to detect motion states. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENGs) have ideal applications in the field of self-powered sensing thanks to their simple structure and flexible working mode. However, the weak operating properties of triboelectric materials in high humidity environments limit the wide application of TENG as sensors. To solve this problem, this work prepared hydrophilic triboelectric materials with natural cellulose as the template and used them for self-powered sensing in high humidity environments. Thanks to the interconnected network of the cellulose scaffold, the complex morphology of the material constructed in concert with Ti 3 C 2 T x during templating provides abundant adsorption sites for water molecules. Over a broad humidity range (40%−90% relative humidity (RH)), the moisture-sensitive triboelectric material can sustain outstanding performance in 150 s with high sensitivity (0.8/1%). The cellulose template-based triboelectric material transmits electrical signals to the user interface wirelessly, enabling self-powered sensing in high humidity environments. This study provides a novel strategy for the design and preparation of high-performance triboelectric materials using cellulose as a template and promotes the study of self-powered sensing in high humidity environments. [Display omitted] • Preparation of a cellulose template-based triboelectric material for high humidity. • The material has high sensitivity and high stability over a wide humidity range. • The material enables humidity sensing and respiration monitoring in high humidity. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerator (TENG) has attracted much interest due to its efficiency, flexibility and cost-effectiveness to harvest wasted mechanical energy. However, the relationship between the chemical composition and output performance of triboelectric materials is still not completely revealed. As an attempt to understand the structure-performance relationship at the molecular level, representative fluorinated poly (arylene ether)s with varying content of electron-donating groups (fluorene groups) in the backbone are synthesized and compared in the performance of TENGs. The structure-dependent performance of triboelectric materials in TENGs is closely related to the potential energy difference (∆ E) between the HOMO energy level of the positive material and the LUMO energy level of the negative material. With an introduction of 50 mol% fluorene groups and the smaller ∆ E , the fluorinated poly (arylene ether) (DFAFW50) contacting with PEEK provides the best output performance of the TENG, and remains stable output performance in 120,000 cycles. For fluorinated poly (arylene ether)s, the introduction of electron-donating groups makes materials tend to lose electrons. Within this effort, a potential molecular design protocol is proposed to develop high-performance positive and negative triboelectric materials applicable in TENGs. [Display omitted] • TENGs based on fluorinated poly (arylene ether)s with varying fluorene groups are built and compared. • The fluorene groups could introduce traps, thereby improving the output performance of fluorinated poly (arylene ether)s. • The smaller ∆E between HOMO and LUMO energy level of triboelectric materials interprets the TENG performance enhancement. • A bridge among TENG property, molecular structure and orbital energy level is built to direct triboelectric material design. [ABSTRACT FROM AUTHOR]

Thermal and Fire hazards result in numerous damage to human life and property. The early detection and instant communication of potential hazards using environmentally sustainable sensors before they occur would significantly reduce the negative impact on the environment while saving lives and property from destruction. Here-in, for the first time, a self-powered thermal and fire hazard sensor was designed by coupling gravitational potential energy to the triboelectric effect to generate electric signals. Harnessing the mechanical integrity and phase change property of the paraffin rod, it is employed as mechanical load support and thermal receptor in the sensor. Furthermore, the sensor was integrated with several communication interfaces such as liquid crystal display (LCD), Wi-Fi emitter, light-emitting diode (LED) light, IoT network, and mobile phone. The sensor exhibited an instant response (∼0 s response time) at temperature ranges between 80 and 89 °C. [Display omitted] • Self-powered thermal hazard sensor is fabricated. • Potential energy is employed as assisting force. • 3D Electric vehicle simulation is presented. • LCD screen, Mobile phone, Wi-Fi and IoT network integration. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENGs) with high energy conversion efficiency and sustainable development are expected to alleviate the pressure of energy and the environment. Exploring factors affecting triboelectric materials is the key to promote output performance of power and charge density. Here, we have synthesized two kinds of organic compounds with different substituent groups (methoxy and nitryl group) to study the electronic effect on organic TENG. The triboelectric test results showed that the organic compounds carrying methoxy and nitryl groups have higher output performances than the original structure. The introduction of methoxy and nitryl groups did change the electron distribution of the entire structure and narrow the band gap of the original structure. The TENG assembled by organic compounds could not only charge micro capacitors instantaneously, but also retained durable stability of more than 50,000 working cycles, and lighted 1054 commercial LED lamps. The static inductive effect in organic triboelectric materials can greatly improve the output performance of organic triboelectric materials. Static inductive effect in organic triboelectric materials can change the electron cloud density distribution of the original structure, which increases the delocalization of electrons, reduces the electron transition energy, produces more contact electrons, and greatly improves the output performance of organic triboelectric materials. [Display omitted] • Two series of pyran derivatives with triboelectric performance were designed and synthesized. • The static induction effects can act as a novel enhancement strategy for output performance of TENG. • The TENG can retain durable stability of more than 50,000 working cycles, and light 1054 commercial LED lamps. • The static inductive effect can change the electron distribution of the molecular structure and short the band gap. [ABSTRACT FROM AUTHOR]

The emerging mechanical functional metamaterials reported with promising mechanoelectrical characteristics bring increasing attention to structurally functional materials. It is essential to deploy mechanical metamaterials in energy materials for effective triggering and controllable mechanoelectrical response. This study reports origami tribo-metamaterials (OTMs) that design triboelectric materials in the origami-enabled, tubular metamaterials. The octagonal, hexagonal, and conical origami units are deployed as the metamaterial substrates to trigger the triboelectric pairs for mechanoelectrical multistability. For the octagonal OTM configuration with the triboelectric pair of fluorinated ethylene propylene-paper, the peak open-circuit voltage, short-circuit current, and transferred charge are obtained as 206.4 V, 4.66 μA, and 0.38 μC, respectively, and the maximum instantaneous output power density is 0.96 μW/cm 2 with the load resistance of 20 MΩ. The OTM takes advantage of the origami metamaterials to obtain the multistable force-displacement response as effective stimuli for the triboelectric materials, which leads to tunable mechanoelectrical performance for speed and weight sensing and energy harvesting. The proposed OTM not only offers a strategy to structurally design energy materials to achieve desirable mechanoelectrical response, but also provides a guideline for the applications of mechanical functional metamaterials in practice.

Non-contact mode triboelectric nanogenerators effectively avoid physical contact between two triboelectric materials and achieve long-term reliable operation, providing broad application prospects in the field of self-powered sensing. However, the low surface charge density of triboelectric materials restricts application of contactless sensing. Herein, by controlling Rayleigh Instability deformation of the spinning jet and vapor-induced phase separation during electrostatic spinning, a polyvinylidene fluoride@Mxene (Ti 3 C 2 T x ) composite film with spheres multiple physical network structures is prepared and utilized as the triboelectric material of a self-powered contactless sensor. The structure of the composite film and high conductivity of Ti 3 C 2 T x provide triboelectric materials with high output performance (charge output and power output up to 128 µC m -2 and 200 µW cm -2 at 2 Hz) and high output stability. The self-powered contactless sensor shows excellent speed sensitivity (1.175 Vs m -1 ). Additionally, it could accurately identify the motion states such as running (55 mV), jumping (105 mV), and walking (40 mV) within the range of 70 cm, and present the signals in different pop forms. This work lays a solid foundation for the development and application of high-performance triboelectric materials, and has guiding significance for the research of self-powered contactless sensing., (© 2022 Wiley-VCH GmbH.)

Triboelectric nanogenerators (TENGs) are devices that convert external mechanical energy into electricity by combining the triboelectric effect and electrostatic induction. As a new mechanical energy harvesting system, TENGs have demonstrated high vitality and great advantage, which hold great promise for applications in various areas of the future society. Over the past few years, the exponential growth of many new classes of polymeric materials for TENGs has been demonstrated. This review presents and evaluates the range of polymer materials for TENGs, and also attempts to assess the influence of modern polymer chemistry on the development of advanced materials for TENGs. Among the most widely used polymer materials for TENGs, polymer-containing electrodes based on metal, carbon and conjugated polymers, as well as polymer triboelectric materials, which are subdivided into synthetic and natural polymers, are identified. The analysis of the use of biocompatible, biodegradable, humidity-resistant and pressure-resistant polymers in TENGs is carried out. Particular attention is paid to the use of self-healing and shape memory polymers as components of TENGs. Finally, the problems and prospects for the development of polymer materials for TENGs are outlined. [ABSTRACT FROM AUTHOR]

Composites' interface is the contact area between filler and matrix, which is a critical issue in composites' permittivity and thereby of great value to improve friction composites' performance in triboelectric nanogenerators (TENGs). However, composites' interfacial influence on triboelectric performance was not clear in past years even numerous composites were prepared, which limited materials' advance of triboelectric performance. Here, a systematic investigation about the composites' interfacial influence was performed on liquid doping polydimethylsiloxane (PDMS) composites, in which interfacial area and compatibility were found with great importance to composites' permittivity and triboelectric performance. Through high preparation stirring speed and appropriate surfactant additive, interfacial modification of enlarging interfacial area and compatible interface was facilely achieved. The as-prepared composites' permittivity and triboelectric performance were remarkably promoted as compared to composites without interfacial modification, achieving 8.1-fold in output voltage and 9.5-fold in output current of pristine PDMS. Further, the composites were applied to assemble TENG for energy harvesting and movement detection. This work revealed the interface properties' influence on composites permittivity and further demonstrated the importance of interfacial modification for enhancement of triboelectric performance, illustrating that the interface issues should be taken into consideration in doping triboelectric composites for high output performance TENG. The interface between filler and matrix is of great value for improvement of composites' permittivity and triboelectric performance. However, composites' interfacial influence on triboelectric performance was not in the view of researchers in past years, which limited materials' advance of triboelectric performance. Through high preparation stirring speed and appropriate surfactant additive, interface modification which included enlarging interfacial area and compatible interface was facilely achieved and the composites' permittivity as well as triboelectric performance were thus remarkably promoted on the basis of composites with non-modified interface. The as-prepared composites' triboelectric performance reached 8.1-fold in output voltage and 9.5-fold in output current of pristine PDMS, demonstrating the great value of interface modification in triboelectric performance enhancement. This work revealed the interface properties' influence on composites permittivity and further demonstrated the importance of interfacial modification for enhancement of triboelectric performance, illustrating that the interface issues should be taken into consideration in doping triboelectric composites for high output performance TENG. Image 1 • Composites' interface is critical in permittivity and triboelectric performance. • A systematic study of interfacial influence was performed on liquid doping PDMS. • Interfacial area and compatibility were important in interface modification. • Results of investigation were exploited to maximize the triboelectric performance. • This work reveals the value of interface modification to triboelectric composites. [ABSTRACT FROM AUTHOR]

The modification or functionalization of triboelectric materials is of great importance for improving triboelectric nanogenerator's triboelectric performance. Traditionally, chemical introduction was the major method for functionalization of TENG materials which relied on certain reactive molecules and complex chemical process. The variety of functionalization was limited as majority functionalization molecules such as halogens are not chemical reactive. Here, high permittivity liquid was dispersed in polydimethylsiloxane (PDMS) matrix by emulsion mixing and regarded as functional molecules micro-carrier for functionalization of triboelectric materials. Due to the solubility of liquid, functionalized PDMS composite could be facilely fabricated by corresponding functional additive dissolved liquid, avoiding functional additive's necessity of chemical reactivity and indicating great extensibility in functionalized triboelectric materials. Fluoroethylene carbonate (FEC) additive for fluorine functionalization and benzyl chloride additive for chloride functionalization were studied for demonstration of this concept. The PDMS composite possessed high permittivity and functional property synchronously and resulted enhancement of 5.7-fold in output voltage, 5.4-fold in current and 44.8-fold in power density as compared with pristine PDMS, which was obtained by fluorine functionalized composite, PDMS-FHD45. This work demonstrated that functional additive liquid doping composite was a promising method for functionalization of triboelectric materials for great extensibility. A facile method was developed for functionalization of triboelectric materials by employing liquid droplets in PDMS-HD composite as functional molecules micro-carriers via corresponding functional additive in liquid, such as FEC additive for fluorine functionalization and benzyl chloride additive for chloride functionalization, endowing the composites with high permittivity and functional property synchronously and inducing significant enhancement in triboelectric performance. Image 1 • TENG materials were functionalized by high permittivity liquid doping material as functional molecules micro-carrier. • It does not rely on chemical reaction and exhibits great extensibility with functional additive dissolved liquid. • Two kinds of functional additive were demonstrated in significant enhancement of power density of TENGs. • This is a general method for functionalization of TENG by liquid doping material as micro-carrier of functional molecules. [ABSTRACT FROM AUTHOR]

Here, a thin and foldable porous reduced graphene oxide (rGO) fabricated by a solvent casting method (SC-rGO) is introduced. The SC-rGO is superior to aluminum as a positive triboelectric material in triboelectric nanogenerators (TENGs), significantly enhancing TENG output performance. The film shows extremely foldable features, where it could be folded by 1/16 size. The electrical properties and device performance of SC-rGO are optimized varying thicknesses from 5 to 30 µm. A 30 µm thick TENG with a non-annealed SC-rGO film (STENG) shows the highest output of about 255 µW cm -2 due to its high carrier concentration, low work function, and high surface area. After annealing, STENG performance is optimized with a 10 µm thick SC-rGO because their work functions decreases, while the corresponding carrier concentrations decrease according to the thickness of the SC-rGO films. The SC-rGO films are highly durable and stable, where their output and conductivity show negligible changes after 100 000 cycles of mechanical deformation. A large SC-rGO with a size of 13 × 3 cm 2 is fabricated and is attached inside a person's arm to demonstrate the shape-adaptive characteristics. Consequently, 170 V is obtained and it turns on 19 green light emitting diodes by simply touching the STENG., (© 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Nanomaterial-based generators are a highly promising power supply for micro/nanoscale devices, capable of directly harvesting energy from ambient sources without the need for batteries. These generators have been designed within four main types: piezoelectric, triboelectric, thermoelectric, and electret effects, and consist of ZnO-based, silicon-based, ferroelectric-material-based, polymer-based, and graphene-based examples. The representative achievements, current challenges, and future prospects of these nanogenerators are discussed., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Negatively polarized ferroelectric polymer β-P(VDF-TrFE) shows higher positive triboelectric properties than skin, which could lead to new medical applications. Kelvin force microscope measurements and triboelectric nanogenerator characterizations are performed to demonstrate this new property. In addition, how many negative charges are exchanged by contact electrification between the negatively polarized β-P(VDF-TrFE) and the skin is estimated., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)