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

The operation cost of an intelligent high-speed train system is greatly increased by the enormous energy demand of large-scale signal and sensor networks. However, the wind energy generated by high-speed trains is completely neglected. Herein, a wind-energy-harvesting device, which is based on an elastic rotation triboelectric nanogenerator (ER-TENG), is fabricated to harvest the wind energy generated by high-speed moving trains and power the relevant signal and sensing devices. Due to the significant decrease in friction force resulting from reasonable material selection and elastic structure design, the energy-harvesting efficiency of an ER-TENG is doubled and the durability is increased by 4 times compared to the same characteristics of a conventional rotation sliding triboelectric nanogenerator (RS-TENG). Our findings not only provide an in situ energy-harvesting pattern for an intelligent high-speed rail system by recovering the otherwise wasted wind energy generated by high-speed trains but also offer a potential strategy for large-scale wind energy harvesting by TENGs.

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.

Broadening the application area of the triboelectric nanogenerators (TENGs) is one of the research emphases in the study of the TENGs, whose output characteristic is high voltage with low current. Here we design a self-powered electrospinning system, which is composed of a rotating-disk TENG (R-TENG), a voltage-doubling rectifying circuit (VDRC), and a simple spinneret. The R-TENG can generate an alternating voltage up to 1400 V. By using a voltage-doubling rectifying circuit, a maximum constant direct voltage of 8.0 kV can be obtained under the optimal configuration and is able to power the electrospinning system for fabricating various polymer nanofibers, such as polyethylene terephthalate (PET), polyamide-6 (PA6), polyacrylonitrile (PAN), polyvinylidene difluoride (PVDF), and thermoplastic polyurethanes (TPU). The system demonstrates the capability of a TENG for high-voltage applications, such as manufacturing nanofibers by electrospinning.

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The sliding‐mode triboelectric nanogenerator (TENG) exhibits higher charge transfer efficiency for extracting mechanical energy than the contact–separation mode TENG, but the energy loss induced by air breakdown as well as the inferior durability seriously limits its practical applications. Here, an effective strategy via interface liquid lubrication is proposed for enhancing output performance of both sliding‐mode alternative current TENG (AC‐TENG) and direct current TENG (DC‐TENG). Due to the improved breakdown field strength requirement and reduced electrostatic field strength in the microgap between the triboelectric layer and electrode, interface liquid lubrication suppresses the interfacial electrostatic breakdown and reduces charge loss after the triboelectrification process, and thus more electrostatic charges are harvested by the AC‐TENG via electrostatic induction and the DC‐TENG via electrostatic breakdown. The maximum output power density of the lubricated sliding‐mode TENG is enhanced by more than 50% (3.45 W m−2 Hz−1) compared to the device without lubrication, and shows excellent durability over more than 500 000 operation cycles. This work provides an effective approach to improve the electric performance and durability of sliding‐mode AC‐TENG and DC‐TENG, which further promotes the practical applications of TENGs.

Surface plasmon resonance (SPR) has been intensively studied and widely employed for light trapping and absorption enhancement. In the mid-infrared and terahertz (THz) regime, graphene supports tunable SPR via manipulating its Fermi energy and enhances light-matter interaction at the selected wavelength. Most previous studies have concentrated on the absorption enhancement in graphene itself while little attention has been paid to trapping light and enhancing the light absorption in other light-absorbing materials with graphene SPR. In this work, periodic arrays of graphene rings are proposed to introduce tunable light trapping with good angle polarization tolerance and enhance the absorption in the surrounding light-absorbing materials by more than one order of magnitude. Moreover, the design principle here could be set as a template to achieve multi-band plasmonic absorption enhancement by introducing more graphene concentric rings into each unit cell. This work not only opens up new ways of employing graphene SPR, but also leads to practical applications in high-performance simultaneous multi-color photodetection with high efficiency and tunable spectral selectivity.

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