Triboelectric Materials Research Articles

Directional Moisture-Wicking Triboelectric Materials Enabled by Laplace Pressure Differences.

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.

Diminish charge loss by mica incorporation into nylon nanofibers for performance enhancement of triboelectric nanogenerators operating in harsh ambient

The triboelectric nanogenerator (TENG) is a fascinating energy-harvesting device that utilizes the triboelectric effect caused by contact electrification and electrostatic induction. Nylon 66 is used widely in TENG applications because it is a representative tribo-positive polymer with excellent biocompatibility. On the other hand, the generated charges are vulnerable to discharge due to moisture in the air, which impedes the TENG performance in harsh environments. Moreover, the dielectric loss, which generates heat by consuming the considerable electric charge in triboelectric materials, significantly degrades the TENG performances. This study fabricated the composite nanofiber (NF) structure of nylon 66 and mica, which has excellent electrical insulation, low dielectric loss, high thermal conductivity, and enhanced tribo-positive properties, to circumvent these problems. Embedding the mica into the nylon NFs enhanced the TENG performance and prevented performance degradation even in harsh environments at a relative humidity of 70%. Furthermore, after 100,000 cycles of friction, the nylon/mica composite NFs showed smaller temperature increments than the pristine nylon NF because of the low dielectric loss and efficient heat dissipation of the mica. The nylon/mica composite NFs were applied to a sustainable and wearable power generator operating in a humid and hot environment by attaching the device to the forearm and soles of the feet. The generators were efficient enough to turn on 80 light-emitting diodes.

B4C/PVDF-based triboelectric nanogenerator: Achieving high wear-resistance and thermal conductivity

Triboelectric active composites that are built with high thermal conductivity and wear-resistance are of prime importance for the long-term operation of triboelectric nanogenerators (TENGs) in harsh environments. In this paper, it’s demonstrated that the introduction of B4C particles into poly(vinylidene fluoride) (PVDF) leads to a thermal conductivity of 0.727 W/(m·k), which is 600 % higher than that of pure PVDF film, and a significant reduction of 39.7 % in the average friction mass loss of the B4C/PVDF. Enhanced anti-corrosion and electrical output performance are also observed, including an open-circuit voltage of 155.4 V, a short-circuit current of 7.9 μA, as well as a maximum output power density of 0.33 W/m2, which are 2.6, 6, and 12 times higher than those of pure PVDF devices, respectively. Interestingly, such a performance grows steadily, rather than degrades, with the operation time, which is sharply differentiated from that observed from other common composites and may be partly ascribed to the roughened surface of the composite film. This work demonstrates an effective strategy for improving the wear resistance and thermal conductivity of the triboelectric material for high-performance energy harvesting and self-powered sensing that are based on BP-TENG for long-term operation.

Bifunctional binder-free ZnCuSe2 nanostructures/carbon fabric-based triboelectric nanogenerator and supercapacitor for self-charging hybrid power system application

Herein, we report a simple self-charging hybrid power system (SCHPS) based on binder-free zinc copper selenide nanostructures (ZnCuSe2 NSs) deposited carbon fabric (CF) (i.e., ZnCuSe2/CF), which is used as an active material in the fabrication of supercapacitor (SC) and triboelectric nanogenerator (TENG). At first, a binder-free ZnCuSe2/CF was synthesized via a simple and facial hydrothermal synthesis approach, and the electrochemical properties of the obtained ZnCuSe2/CF were evaluated by fabricating a symmetric quasi-solid-state SC (SQSSC). The ZCS-2 (Zn:Cu ratio of 2:1) material deposited CF-based SQSSC exhibited good electrochemical properties, and the obtained maximum energy and power densities were 7.5 Wh kg–1 and 683.3 W kg–1, respectively with 97.6 % capacitance retention after 30,000 cycles. Furthermore, the ZnCuSe2/CF was coated with silicone rubber elastomer using a doctor blade technique, which is used as a negative triboelectric material in the fabrication of the multiple TENG (M-TENG). The fabricated M-TENG exhibited excellent electrical output performance, and the robustness and mechanical stability of the device were studied systematically. The practicality and applicability of the proposed M-TENG and SQSSC were systematically investigated by powering various low-power portable electronic components. Finally, the SQSSC was combined with the M-TENG to construct a SCHPS. The fabricated SCHPS provides a feasible solution for sustainable power supply, and it shows great potential in self-powered portable electronic device applications.

Boosting the triboelectric performances of biowaste chitosan keratin triboelectric nanogenerator using carbon composite film as charge storage and charge recombination blocking intermediate layer

Environmental conservation efforts are promoting energy-generation technologies that avoid the use of highly polluting fuels and promote the reuse of waste materials. Advances in triboelectric nanogenerators (TENGs) have led to the progress in harvesting energy from ambient mechanical sources and powering small devices and sensors while being compact, flexible, biocompatible, and eco-friendly. Nevertheless, the practical applications of TENG have limitations. Therefore, the development of TENG with excellent triboelectric performance, eco-friendliness, and low cost is crucial. Consequently, an environmentally friendly, inexpensive TENG device with outstanding triboelectric performance was designed using keratin-enhanced chitosan as a tribo-positive material, a carbon film as an intermediate layer, and polytetrafluoroethylene as a triboelectric negative material. The device was purposely designed to simultaneously play a role in waste treatment and efficient green energy harvesting. Therefore, keratin was extracted from recycled fur, and a carbon film was selected to enhance the triboelectric performance because of its excellent electrical conductivity and dielectric constant. The triboelectric properties of a chitosan keratin intermediate layer (CKI)-TENG were systematically investigated. Practical applications of the CKI-TENG in charging electronic devices and waste-noise harvesting were also studied. The developed CKI TENG exhibited outstanding triboelectric performance compared to a TENG device without an intermediate layer. Particularly, the charge transfer, output voltage, and power density was improved by 19%, 46%, and 60%, respectively, compared to the output of the chitosan-keratin (CK) TENG device. It also exhibited outstanding cyclic and charging-discharging stabilities. In addition, the power density of the developed CKI TENG was higher than that of previously reported TENG devices. Thus, it can play a significant role in green and clean energy generation and the utilization of the harvested energy in practical applications, such as biomedical sensors, charging electronic devices, smart textiles, and sensors.

Preparation of Polyaniline-Modified Cellulose/PDMS Composite Triboelectric Material and Application of Its Pretreatment in MOW Pulp.

Self-powered electronic equipment has rapidly developed in the fields of sensing, motion monitoring, and energy collection, posing a greater challenge to triboelectric materials. Triboelectric materials need to enhance their electrical conductivity and mechanical strength to address the increasing demand for stability and to mitigate unpredictable physical damage. In this study, polyaniline-modified cellulose was prepared by means of in situ polymerization and compounded with polydimethylsiloxane, resulting in a triboelectric material with enhanced strength and conductivity. The material was fabricated into a tubular triboelectric nanogenerator (TENG) (G-TENG), and an electrocatalytic pretreatment of mixed office waste paper (MOW) pulp was performed using papermaking white water as the flowing liquid to improve the deinking performance. The electrical output performance of G-TENG is highest at a flow rate of 400 mL/min, producing a voltage of 22.76 V and a current of 1.024 μA. Moreover, the deinking effect of MOW was enhanced after the electrical pretreatment. This study explores the potential application of G-TENG as a self-powered sensor power supply and emphasizes its prospect as an energy collection device.

Advancing triboelectric human machine interfaces with core-sheath nanocomposite fibres: Enhanced flexibility and motion identification via machine learning

The rapid development of triboelectric nanogenerators (TENGs) has led to sustainable sensing applications as triboelectric interfaces for activity/pattern recognition in human machine interaction (HMI). In this work, core-sheath nanofibres were synthesized and employed as triboelectric materials for constructing new TENGs. These electrospun fibres of novel design consist of a nanocomposite core comprised of polystyrene (PS) and molybdenum disulfide (MoS2) nanoplatelets, and a sheath made of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). Compared to high performance TENGs based on neat PVDF-HFP nanofibres tribolayer, these new TENGs achieved open circuit voltage of 1944 V and short-circuit current of 40.3 μA, yielding a total improvement of 284% and 783%, respectively, attributed from the highly efficient charge storage and binding capabilities from the MoS2 nanoplatelets and the PS core. To harness the remarkable performances of these new TENGs, a touch input component was developed, designed to work in conjunction with machine learning algorithms. The triboelectric interfaces exhibited high accuracy in user identification, capable of recognizing individual users with up to 86% average accuracy, under identical press patterns applied by different users. This paves the way for future development of machine learning assisted HMI enabled by TENGs for next generation sustainable communication networks.

Triboelectric haptic sensors based on fluorinated cellulose/PDMS composite porous films for monitoring joint flexion and smart writing

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 (VOC of 189.70 V, ISC of 0.88 μA and QSC 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.

A Novel Mechano-Synthesized Zeolitic Tetrazolate Framework for a High-Performance Triboelectric Nanogenerator and Self-Powered Selective Neurochemical Detection.

Designing a high-performing triboelectric novel material with eco-friendly, rapid, and cost-effective synthesis is the future of material research in triboelectric nanogenerators (TENG). We report a mechanochemical ball mill synthesis of a zeolitic tetrazolate framework (ZTF-8) that is isostructural with the well-known zeolitic imidazolate framework ZIF-8. ZTF-8 is extremely stable in water, 0.1 M aqueous acid/base solutions for 75 days at 25 °C, and boiling water (100 °C) for 7 days. Kelvin probe force microscopy and molecular electrostatic surface potential computational analysis exhibited that ZTF-8 has a very high positive surface potential. Atomic force microscopy and three-dimensional digital microscopy studies reveal the high roughness profile in the ZTF-8 film. The unique structure, exceptional acid/base stability, good dielectric property, and high roughness profile combined with the extremely electropositive nature of ZTF-8 make it a suitable candidate as a polymer-free triboelectric positive material in TENG with outstanding performance (power density of 720 mW/m2). High triboelectric output was further validated using the COMSOL Multiphysics simulation tool. Simple mechanical hand tapping of the ZTF-based TENG (ZTF-TENG) device generates high electric output, which was practically used to power numerous low-powered devices like tally counter, clinical thermometer, and digital clock and also illuminates 125 light-emitting diodes. In addition, the efficiency of ZTF-TENG was utilized as a self-powered device for a selective dopamine (DA) sensor with good sensitivity (377.76 mV/μM/cm2), wide range linearity (5-120 μM), and excellent limit of detection (0.42 μM).

Enhancing the Humidity Resistance of Triboelectric Nanogenerators: A Review.

Triboelectric nanogenerators (TENGs) are sustainable energy resources for powering electronic devices from miniature to large-scale applications. However, their output performance and stability can deteriorate significantly when TENGs are exposed to moisture or humidity caused by the ambient environment or human physiological activities. This review provides an overview of the recent research advancements in enhancing the humidity resistance of TENGs. Various approaches have been reviewed including encapsulation techniques, surface modification of triboelectric materials to augment hydrophobicity or superhydrophobicity, the creation of fibrous architectures for effective moisture dissipation, leveraging water assistance for TENG performance enhancement, and other strategies like charge excitation. These research efforts contribute to the improvement of environmental adaptability and lead to expanded practical TENG applications both as energy harvesters and self-powered sensors. The efficacy of these strategies and future challenges are also discussed to facilitate the continued development of resilient TENGs in high humidity environments.

Multistage amine-modified cellulose nanofibrils as high-performance positive triboelectric materials

Multistage amine-modified cellulose nanofibrils as high-performance positive triboelectric materials

60Co-γ Irradiation-Induced Shift and Polarity Reversal in the Triboelectric Series of Poly(ether sulfone)s.

The sensitivity of triboelectric nanogenerators (TENGs) to the surface charge density highlights the significance of triboelectric materials and their modifications. Efforts have been directed toward developing effective strategies for increasing the surface charge density, expanding the potential applications of TENGs. This study proposes the use of irradiation technology for grafting to modify the electron-donating capability of poly(ether sulfone) (PES), thereby affording a dual benefit of enhancing the surface charge density and inducing a shift in the position of PES from negative to positive within the triboelectric series. The TENG based on grafted PES has resulted in a significant 3-fold increase in surface charge density compared to that of pristine PES, reaching 263 μC m-2. The surface charge density can be further increased to 502 μC m-2 through charge pumping. Notably, irradiation technology presents advantages over chemical grafting methods, particularly in terms of sustainability and environmental friendliness. This innovative approach shows great potential in advancing the domain of TENGs.

Highly Semiconducting One-Dimensional Porous ZnO Nanorod Array Nanogenerators for Mechanical Energy Harvesting Functions

The development of energy harvesters based on inexpensive inorganic materials has attracted considerable attention to envisage next-generation self-powered electronic devices. In this work, we presented surface modification of ZnO nanorods (NRs) by thermochemical reaction using photoresist (PR) as an etching source. The morphological and microstructural properties of surface-etched ZnO NRs (M: ZnO) were systematically studied in detail through SEM and HRTEM. The morphological results show that the surface-etched NRs possess nanofiber-like porous structures and are penetrated throughout the NRs with high surface area. We fabricated triboelectric nanogenerators (TENG) using M: ZnO NRs with poly (dimethylsiloxane) (PDMS) as negative triboelectric material and mica as positive triboelectric material. The prepared M: ZnO NR TENG successfully delivered an output voltage of up to 20 V and a current density of 3.2 μA cm−2, which is ∼1.5 times higher than those observed for smooth ZnO NRs, respectively. The prepared M: ZnO NR TENG device can be able to lit 24 red light-emitting diodes (LEDs) as the power source. Finally, to demonstrate the practical applications of M: ZnO NR TENG, it was attached to the human body (elbow, knee, wrist, and heel) and efficiently harvested the energy from daily human activities.

Controlling electrospun nanofibers surface morphology using relative humidity for enhancing triboelectric nanogenerator performance

We employ an electrospinning technique to precisely modulate nanofibers diameter by varying humidity, impacting surface morphology, roughness and frictional contact-area of triboelectric materials. This leads to an augmentation of surface charge density, promoting generation of surface charges on triboelectric materials. MXene (MX) and cellulose acetate (CA) form an effective pairing, with optimized sample CA-40_MX-40 at 40 % RH displaying five-fold increase in voltage compared to CA-20_MX-20. This sample achieves a peak power density of 2351.1 mW/m2 at 106 Ω, capable of powering LEDs. These findings introduce a viable fabrication technique to manipulate surface roughness, promising significant avenue for sustainable high-performance TENGs.

Advanced Triboelectric Applications of Biomass-Derived Materials: A Comprehensive Review.

The utilization of triboelectric materials has gained considerable attention in recent years, offering a sustainable approach to energy harvesting and sensing technologies. Biomass-derived materials, owing to their abundance, renewability, and biocompatibility, offer promising avenues for enhancing the performance and versatility of triboelectric devices. This paper explores the synthesis and characterization of biomass-derived materials, their integration into triboelectric nanogenerators (TENGs), and their applications in energy harvesting, self-powered sensors, and environmental monitoring. This review presents an overview of the emerging field of advanced triboelectric applications that utilize the unique properties of biomass-derived materials. Additionally, it addresses the challenges and opportunities in employing biomass-derived materials for triboelectric applications, emphasizing the potential for sustainable and eco-friendly energy solutions.

Superhydrophobic Triboelectric Structural Materials Enabled by Hierarchical Spatial Assembly

AbstractNon‐contact intelligent sensing technology is a key player in the data acquisition and environmental monitoring framework of the Internet of Everything, laying the groundwork for the realization of highly integrated intelligent network systems. However, environmental factors continue to be a major challenge in the process of real‐time monitoring and feedback of objects, constraining the stability and accuracy of the sensing signals. In this study, a hierarchical spatial assembly strategy is implemented to effectively integrate an intermediate energy storage layer with superhydrophobic surfaces (CA = 162 ± 2.5°), resulting in the development of a moisture‐resistant triboelectric structural materials with stable monitoring and tracking capabilities. The moisture‐resistant self‐powered sensor constructed from this triboelectric structural material operates effectively in extreme humidity conditions (99% RH) with a full‐scale output retention rate of 95.2%, and is capable of accurately sensing human activity from the distance of 3 m. Importantly, the sensor can also effectively detect vehicle states during operation and perform real‐time monitoring of the vehicle's surrounding environment. This study not only overcomes the long‐standing challenges of accuracy and stability in high humidity for sensors but also advances the development of sustainable, interconnected intelligent systems for the Internet of Everything in extreme environmental conditions.

Recent advances in high charge density triboelectric nanogenerators

Abstract Triboelectric materials with high charge density are the building-block for the commercial application of triboelectric nanogenerators (TENGs). Unstable dynamic processes influence the change of the charge density on the surface and inside of triboelectric materials. The charge density of triboelectric materials depends on the surface and the internal charge transfer processes. The focus of this review is on recent advances in high charge density triboelectric materials and advances in the fabrication of TENGs. We summarize the existing strategies for achieving high charge density in triboelectric materials as well as their fundamental properties. We then review current optimization methods for regulating dynamic charge transfer processes to increase the output charge density: first, increasing charge injection and limiting charge dissipation to achieve a high average surface charge density, and second, regulating the internal charge transfer process and storing charge in triboelectric materials to increase the output charge density. Finally, we present the challenges and prospects in developing high-performance triboelectric materials.

Nanomaterials for advanced energy applications: Recent advancements and future trends

Nowadays, one of the most promising and significant challenges for our society is achieving highly efficient energy utilization. To address the upcoming demands in energy applications, which demonstrate considerable potential for future trends, continuous efforts are necessary to develop improved and higher-performing inorganic multifunctional nanomaterials. Multifunctional inorganic nanomaterials have been extensively researched to meet the requirements of various energy applications or to enhance them further. Specific attention is given to inorganic nanomaterials for advanced energy storage, conservation, transmission, and conversion applications, which strongly rely on the optical, mechanical, thermal, catalytic, and electrical properties of energy materials. At the nanometer-scale range, triboelectric, piezoelectric, thermoelectric, electrochromic, and photovoltaic materials have made significant contributions to numerous energy sector applications. Functional inorganic materials possess unique properties, including excellent thermal and electrical conductivity, chemical stability, and a large surface area, which enhance their competitiveness in energy-related applications. Herein, recent research, development, and advances in inorganic multifunctional nanomaterials to enhance their performance are discussed, highlighting how devices combine the functionalities of nanomaterials. In this manner, we aim to provide insights into future applications and elucidate the ongoing research challenges currently facing this field.

Fully‐Recyclable Green and Fire‐Resistant Triboelectric Elastomer via Geometrical Synergistic Fillers and Its Applications for Smart Firefighting Boots

AbstractWearable 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.

Strongly correlated electron system NiWO4: A new family of materials for triboelectrics using inherent Coulombic repulsion

The strongly correlated electron system (SCES) insulators promise a wide range of intriguing physical phenomena arising from the exotic charge gap depending on the strength of the Coulombic repulsion between d and f orbital cations. The SCES exhibits polaron hopping conduction, which requires a higher activation energy for carrier conduction between nearest cations, indicating a strong insulating character with relatively high permittivity. Here, we demonstrate that the NiWO4 SCES insulator, which is formed by Coulombic repulsion between the nearest d orbital of Ni, proposes a suitable triboelectric material unlisted system from conventional metal oxides. The higher degree of freedom in NiWO4 by the lower symmetry of monoclinic structure and an additional selection of composition exhibits high relative permittivity (∼13.8) in a wide range of temperatures (up to 180 ℃). The optimized simple mixture of NiWO4 and PDMS (polydimethylsiloxane) for the negatively charged material to triboelectric nanogenerator (TENG) presents 1.78 times higher output compared to the pristine PDMS film-based TENG. NiWO4, considering the physical properties of the SCES determined by Coulombic repulsion strength, paves the way for a new option of TENG materials following the high permittivity.