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Triboelectric nanogenerator (TENG) can convert mechanical energy into electrical energy and has been regarded as a promising portable power source. However, the low output power restricts TENG’s applications in energy harvesters and sensors. Herein, we developed an effective way of increasing TENG’s output power by combining ferroelectricity and conduction of the triboelectric materials. For this purpose, a conductive interlayer modulated ferroelectric nanocomposite was used as the negative triboelectric material. Compared with the conventional ferroelectric nanocomposites based TENG, the transferred triboelectric charge density of the conductive interlayer modulated ferroelectric nanocomposite based TENG can reach 105.70 μC m−2 from 17.50 μC m−2, while the output power density increases to 7.21 W m−2 from 0.11 W m−2. The boosted output performance can be attributed to the existence of a conductive intermediate layer in the negative triboelectric material, which induces charge trapping and enhances ferroelectric polarization of the nanocomposites. Apart from being used as wearable energy harvesters, the TENG device also exhibits a promising application in parachuting surveillance for preventing potential injuries. Furthermore, TENG device has numerous possible application scenarios for future airborne troops. This work provides a brand-new strategy for enhancing contact electrification, showing strong potential in design of high output TENGs.

Ocean waves are one of the most power dense energy sources in the environment. Triboelectric nanogenerators (TENGs) have been demonstrated to effectively harvest mechanical energy carried by low frequency, random/irregular actuation, such as from ocean waves. In this work, a novel design of triboelectric nanogenerator based on the Pelamis snake energy harvester is presented. The sea snake based TENG, with its lightweight structure, was able to harvest energy effectively at low amplitude ocean wave by utilizing charged polytetrafluroethylene balls that would roll due to the wave's curvature. With the integration of springs to connect different segments, the segments are able to bend easily, allowing the enclosed balls to move faster, producing higher output power. The design of an air gap structure allows each segments of the sea snake based TENG to minimize electrostatic induction from ions in sea water, and solve the effect of dielectric shielding from the water on the device performance, as the water, if it is close to the TENG's electrodes, has a detrimental effect causing an increase of the TENG's internal capacitance, which would result in a low voltage with the same amount of charge being transformed. Thus, this illustrates the importance of the air gap structure to minimize low voltage due to high internal capacitance. This further shows the sea snake based triboelectric nanogenerator could be used in actual ocean conditions, such as in high salinity water environment. The added tampered spring to replace the air gap was able to allow the balls on the TENG to move more quickly, as it increased the rotational angle, and the TENG has a maximum power density of 3 W/m3 under actuation. Due to the minimization of dielectric shielding of device performance, the sea snake TENG exhibits a high voltage in simulated water wave conditions.

The ubiquitous sensors have accelerated the realization of Internet of Things (IoT) but also raised challenges to the current overcrowding radio frequency (RF) based communications. The optical wireless communication (OWC) that utilizes the wide optic bandwidth can well solve the spectrum crisis and is an appealing complementary solution to the IoT applications. However, the additional direct current (DC) power supply and complicated modulating and power management circuits may limit the large-scale deployment of OWC systems. In this paper, by integrating with triboelectric nanogenerators (TENGs), the light-emitting diode (LED) could be directly transformed into a wireless transmitter that conveys the information associated with mechanical stimuli without additional power supply. With the customized TENG devices and the help of advanced image processing and machine learning techniques, three demonstrations with functions of optical remote control, pressure sensing, and security authentication, were demonstrated. The concept and results in this paper may greatly broaden the application of IoT through the integration of OWC and TENG.

Developing lightweight, flexible and sustainable sensor networks with miniaturized integration and functionality for the Internet of Things (IoT) remains a challenge and an urgent demand for the next-generation electronic devices. Paper-based electronics, which represents one of the main green electronics in the future, have been considered as one of the most exciting technologies to meet the consumption of the frequently upgraded electronics. Here, we presented an ultrathin (about 200 µm) and lightweight paper-based self-powered system that consists of a paper-based triboelectric/piezoelectric hybrid nanogenerator and a paper-based supercapacitor. Under human motions such as flipping the page and moving the book/document, the as-fabricated self-powered system built-in the smart book/document was capable of sustaining power for portable devices, such as continuously driving LEDs and the temperature/humidity sensor. With the signal-processing circuit, the paper-based system was further developed into a wireless human-machine interaction system for documents management and smart reading. The ultrathin and highly flexible characteristics of the self-powered system not only endow the device with power generation feature for portable devices, but also build up the wireless human-machine interactions in developing potential applications for the IoT.

Nanocomposites consisting of a flexible piezoelectric polymer and a reinforcing phase have shown great potential for constructing high-performance piezoelectric nanogenerators (PENGs). However, the weak interface and poor dispersion of piezoelectric reinforcing phase significantly impair the electromechanical properties (e.g., effective stress/strain, piezoelectric coefficients) of the nanocomposites, thus severely restricting the performance enhancement of the PENGs. In this study, we hydrothermally synthesized the piezoelectric reinforcing phase of BaTiO3 nanowires, and grafted a layer of high-modulus polymethyl methacrylate (PMMA) onto the nanowire surface via surface-initiated polymerization. The PMMA coating layer forms a strong interface between BaTiO3 nanowires and the polymer matrix [i.e., poly(vinylidenefluoride-co-trifluoroethylene)], which efficiently improves dispersion of the BaTiO3 nanowires and stress transfer at the interface, therefore resulting in an enhanced output performance in the fibrous nanocomposite PENGs. The output voltage and current of the PMMA encapsulated BaTiO3 (PMMA@BaTiO3) nanowires-based PENG can reach to 12.6 V and 1.30 μA, with a maximum output power of 4.25 μW, which is 2.2 times and 7.6 times higher than the PENG with unmodified BaTiO3 nanowires and the PENG without BaTiO3 nanowires, respectively. Furthermore, the flexible PENG exhibits great stability that could continuously generate stable electrical pulses for 6000 cycles without any decline. This study provides a feasible approach of interface tailoring for achieving high-performance piezoelectric nanocomposite and shows the promising potential of the fibrous nanocomposites in biomechanical energy harvesters and smart wearable sensors.

The open circuit voltage of a conventional H2-O2 fuel cell is limited to ~1.23 V under atmospheric pressure, which limits the efficiency of the system. Here, we reported a dual-electrolyte microfluidic fuel cell system (DEFC), which could stably deliver an open circuit voltage up to 1.76 V at room temperature under atmospheric pressure, and a peak power density of 145 mW/cm2, improved by 3 times compared with that in single electrolyte mode. When operated in the reverse mode, the microfluidic cell can be used for water electrolysis, demonstrating a water split voltage of ~0.74 V and a round trip voltage efficiency of 83.5% at a current density of 100 mA/cm2. The neutralization energy of the two electrolytes, which could be wasted as heat, can be directly utilized to produce electricity or split water with high efficiency. Given the DEFC's features of high open-circuit voltage, low water splitting voltage, and room-temperature operation condition, the reported DEFCs technology presents a superior route for high-efficiency energy conversion and storage system that could revolutionize the fields of large-scale energy storage and portable power systems.

Triboelectric nanogenerators (TENG) is a promising route for harvesting ambient mechanical energy to obtain clean and renewable electricity. However, the durability of materials still limits its practical applications for continuous operation. Here, a radial-arrayed TENG was integrated with a transmission mechanism, which successfully maximized the sustainable operation with less triboelectric material wear and damage. Through the rational design of the transmission mechanism, triboelectric layers were first charged by the contact electrification due to the wave impact from the sides, and charges were transferred by the electrostatic induction continuously because of the tumbler's design. In this case, frictional resistance between the triboelectric layers were successfully eliminated, which largely enhances its robustness and durability. After running for 500 k cycles, there is only 1.8% degradation. The TENG could convert one single impact into multiple cycles of rotations, which improves the energy harvesting efficiency for sustainably driving and charging commercial electronics, immediately demonstrating the feasibility of the TENG as a practical power source with extended lifetime and durability. Given exceptional durability and unprecedented applicability resulting from novel designs, this work provides an attractive strategy for the study of triboelectric nanogenerator's durability and facilitates the development of the self-powered systems.

Mechanical energy in ambient, such as water wave, wind, vibration, and human activities, is a green energy that is widely distributed and universally achievable. However, this type of energy has ultra-low frequencies and variable amplitudes, so it is rather challenging to collect them at high efficiency. Here we report a pendulum inspired triboelectric nanogenerator (P-TENG), which could not only boost the output frequency multiple times using a pendulum structure, but also hugely improve the harvesting efficiency through a transformation of impact kinetic energy into potential energy. The P-TENG also has ultrahigh sensitivity and active response to mechanical triggering from a random direction and superior durability for long time operation. A single trigger from the environment, the P-TENG shows a continuous electrical output for 120 s at a frequency of 2 Hz, and its output energy of which is 14.2 times larger than the energy of conventional free-standing TENG. Owing to the air gap between the triboelectric layer and electrodes and the mechanism of electrostatic induction, the P-TENG can work with little frictional resistance and surface wearing, largely enhancing its robustness and durability. The network of P-TENGs was successfully demonstrated to scavenge water wave or wind energy as sustainable power sources. Given the features of exceptional output performance, unprecedented robustness and universal applicability resulting from distinctive mechanism and structure, the P-TENG is a promising method to efficiently harvest energy from the ambient environment with possibility contributing to the blue energy.