ABSTRACT
6G communication mainly occurs in the THz band (0.1-10 THz), which can achieve excellent performance. Self-powered THz modulators are essential for achieving better conduction, modulation, and manipulation of THz waves. Herein, a self-powered terahertz modulator, which is based on metamaterials, liquid crystals (LCs), and rotary triboelectric nanogenerators (R-TENGs), is proposed to realize the driving of different array elements. The corresponding designs can achieve an integrated design and preparation method for dynamic spectrum-reconfigurable liquid crystal metamaterials. In addition, for the type of cross-structure metamaterial liquid crystal box, a phase modulation of 1 GHz is achieved at frequencies of 0.117 and 0.161 THz with modulation depths of 13 and 11%, respectively. Because the R-TENG with a multifan blade and circular electrodes can generate 18 peaks of electric output in every rotation, it can successfully provide sufficient frequency alternating-current electric energy to drive the terahertz modulator and achieve a self-powered function. Our findings lay a solid theoretical foundation for further building self-powered THz communication systems and promote the development of a theoretical system for LC-driving spectrum-reconfigurable devices in the THz domain.
ABSTRACT
Due to the simple installation and convenient maintenance, the floating water wave energy harvesting devices have significant economic advantages. Mass power density is the most important index to evaluate the advancement of floating wave energy harvesting devices. Herein, a self-adaptive rotating triboelectric nanogenerator (SR-TENG) with a compound pendulum and a functional gear-set is provided for wave energy harvesting. First, a compound pendulum structure with a low center of gravity and high moment of inertia is obtained by the geometric design and mechanical study. Besides, compared with the previous triboelectric nanogenerator with one-way clutch, SR-TENG can harvest twice the kinetic energy utilization through the functional gear-set. Importantly, depending on the structure design, the SR-TENG obtains the average mass power density of 45.18 mW kg-1 under low frequency driving conditions, which is about 10 times the reference electromagnetic generator with a similar structure and size. This result shows that the SR-TENG has a significant advantage in small water wave energy harvesting. These findings provide an important example of the floating water wave energy harvesting devices.
ABSTRACT
Water splitting for yielding high-purity hydrogen represents the ultimate choice to reduce carbon dioxide emission owing to the superior energy density and zero-pollution emission after combustion. However, the high electricity consumption and requirement of large quantities of pure water impede its large-scale application. Here, a triboelectric nanogenerator (W-TENG) converting offshore wind energy into electricity is proposed for commercial electric energy saving and cost reduction. By introducing PTFE/POM dielectric pairs with matched HOMO/LUMO band gap energy, a high charge density is achieved to promote the output of W-TENG. With the impedance matching design of transformers with the internal resistance of W-TENG, the output current is further enhanced from 1.42 mA to 54.5 mA with a conversion efficiency of more than 92.0%. Furthermore, benefiting from the high electrocatalytic activity (overpotential = 166 mV and Tafel slope = 181.2 mV dec-1) of a carbon paper supported NiCoP-MOF catalyst, natural seawater can be adopted as a resource for in situ hydrogen production without acid or alkaline additives. Therefore, the self-powered seawater electrolysis system achieves a H2 production rate as high as 1273.9 µL min-1 m-2 with a conversion efficiency of 78.9%, demonstrating a more practical strategy for conversion of wind energy into renewable hydrogen energy.
ABSTRACT
The triboelectric nanogenerator shows a broad application potential in wind energy collection and wind speed sensing. However, it is difficult to realize wind energy collection and real-time wind speed monitoring in one simple device without external power support. Here, a high-performance dual-mode triboelectric nanogenerator is proposed to simultaneously collect wind energy efficiently and monitor wind speed in real time, which is composed by an alternating current triboelectric nanogenerator (AC-TENG) and a direct-current triboelectric nanogenerator (DC-TENG). Based on the material optimization, the charge density of the AC-TENG improves by a factor of 1 compared with previous works. Moreover, benefiting from the elastic structure and material optimization to realize a low friction force, the AC-TENG shows an excellent durability and obtains a retention of 87% electric output after 1â¯200â¯000 operation cycles. Meanwhile, thanks to the high charge density and low friction force, the energy-harvesting efficiency of the AC-TENG is doubled. In addition, the DC-TENG not only displays an excellent real-time sensing performance but also can provide gale warning. Our finding exhibits a strategy for efficiently collecting wind energy and achieving fully self-powered and real-time wind speed monitoring.
ABSTRACT
A self-charging power system harvesting random and low-frequency wave energy into electricity provides a promising strategy for the construction of smart oceans. However, the system faces huge challenges of easy corrosion in the marine environment and the utilization of toxic organic electrolytes in energy storage devices. To address the issues above, a seawater supercapacitor (SWSC) for the marine self-charging power system is rationally proposed by using a conductive polymer, polypyrrole with hollow morphology (h-PPy), to enhance the stability and capacitance while using seawater as an eco-friendly electrolyte to reduce the cost and achieve sustainability. The hollow design provides a shortcut for the ion transportation of seawater into the h-PPy electrode, and the SWSC achieves a high power density of 4.32 kW kg-1 under an energy density of 5.12 W h kg-1. Even after 180 days in seawater, h-PPy still endows a mass retention of 99.9%, enabling the SWSC to maintain a stability of 99.3% after 6000 cycles. More importantly, when combined with a TENG module as the marine self-charging power system to harvest wave energy, the system provides a stable output in water wave to drive electronics and sensors, which shows a competitive potential in the smart ocean and marine internet of things.
ABSTRACT
The liquid-solid triboelectric nanogenerator is broadly studied for its self-powered sensing and blue energy harvesting, thanks to its low wear and highly efficient contact. However, the corresponding research studies focusing on deionized-water liquid-solid triboelectric nanogenerators (DL-TENGs) and seawater-type liquid-solid TENGs (SL-TENGs) are rarely being carried out at present. Here, a SL-TENG is fabricated by applying a dielectric film as the organic coating and coated and uncoated steel hull as the two electrodes. Based on the reasonable material selection of the dielectric film, the SL-TENG showed excellent performance, which benefits from the good triboelectrification performance and weak ion adsorption effect. In addition, compared with commercial marine anticorrosive coatings, the friction coefficient of the SL-TENG with the seawater can be reduced 43.8%, which is significantly beneficial to reduce the sailing resistance of ships. More importantly, the uncoated steel electrode can obtain a high potential in highly corrosive seawater, which can enable it to perform the function of marine anticorrosive agents. Our finding provides a potential strategy to evade the marine anticorrosion of ships.
ABSTRACT
Triboelectric nanogenerator (TENG) has presented the huge potential application in distributed energy field which can realize the conversion from dispersed mechanical energy to electric energy. However, the natural characteristic of pulse output for conventional TENG, which means high crest factor, is defective for directly driving electronics. Here, a strategy to convert the pulse alternate current of TENG into a direct current with low crest factor is achieved through introducing a phase difference design into the structure of TENG. As a result, a direct current with a crest factor of 1.07 is obtained in a rotational free-standing TENG (RF-TENG) array at optimum phase difference, where 3D digital printing technology is used to accurately control the parameter of phase difference. Moreover, an adaptable contact mode structure between tribolayer and electrode improves the durability of the RF-TENG array, which can present a stable performance after working 1.2 million cycles. This work provides a combined strategy to obtain a long-lifetime and low crest-factor TENG for its large-scale application in energy harvesting.
ABSTRACT
The liquid-solid triboelectric nanogenerator (LS-TENG) has been demonstrated to harvest energy efficiently through the contact electrification effect between liquid and solid triboelectric materials, which can avoid the wear issue in solid-solid TENG. However, the droplet-based LS-TENG reveals the problems that it generally works with the continuous falling droplets or needs to be fully packaged, which greatly limit its practical application. Here, a droplet-based triboelectric nanogenerator (DB-TENG) with a simple open structure is designed to effectively solve these problems. The nonpackaged DB-TENG can work stably under extreme conditions with high humidity or high concentrations of salt, acid, or alkali solutions, showing the DB-TENGs can be flexibly utilized in all types of working environments with better reliability and lower maintenance costs. It is of great significance that the integrated DB-TENG network array can realize the all-weather ocean energy harvesting. Furthermore, under the simulated ocean wave, a scaled-up DB-TENG with considerable output performance can charge capacitors and drive electrical devices. Overall, the DB-TENG shows many advantages: simple open structure, all-weather working ability, timely supplement of water loss, no tight packaging, wear resistance, suitable for extreme working environments. This work provides a convenient and feasible way toward all-weather wave energy harvesting in real marine environments.
ABSTRACT
An ocean wave contains various marine information, but it is generally difficult to obtain the high-precision quantification to meet the needs of ocean development and utilization. Here, we report a self-powered and high-performance triboelectric ocean-wave spectrum sensor (TOSS) fabricated using a tubular triboelectric nanogenerator (TENG) and hollow ball buoy, which not only can adapt to the measurement of ocean surface water waves in any direction but also can eliminate the influence of seawater on the performance of the sensor. Based on the high-sensitivity advantage of TENG, an ultrahigh sensitivity of 2530 mV mm-1 (which is 100 times higher than that of previous work) and a minimal monitoring error of 0.1% are achieved in monitoring wave height and wave period, respectively. Importantly, six basic ocean-wave parameters (wave height, wave period, wave frequency, wave velocity, wavelength, and wave steepness), wave velocity spectrum, and mechanical energy spectrum have been derived by the electrical signals of TOSS. Our finding not only can provide ocean-wave parameters but also can offer significant and accurate data support for cloud computing of ocean big data.
ABSTRACT
Vibration sensor is very necessary for monitoring the structural health of constructions. However, it is still a major challenge to meet simultaneously real-time monitoring, continuous assessment, and early incident warning in a simple device without a complicated power and analysis system. Here, we report a self-powered vibration sensor system to achieve real-time and continuous detection of the vibration characteristics from a dual-mode triboelectric nanogenerator (AC/DC-TENG), which can produce either alternating current (AC) or direct current (DC) within different operation zones. Within the vibration-safe region, the AC/DC-TENG with AC output not only can continuously assess the vibration characteristics but also can power the signal transmission. More importantly, once the vibration amplitude crosses the danger threshold, the AC converts immediately to DC, meanwhile triggering the alarm system directly to accurately predict the danger of construction. Our self-powered vibration sensor system can serve as a facile tool for accurately monitoring the structural health of constructions.
