The conversion and transmission of blue energy in the ocean are critical issues. By employing triboelectric nanogenerators (TENGs), blue energy can be harvested but the corresponding electricity transmission and storage are still great challenges. In this work, an automatic high‐efficiency self‐powered energy collection and conversion system is proposed that converts blue energy to chemical energy. A gear‐driven unidirectional acceleration TENG is designed to convert disordered and low‐frequency water wave energy to low voltage and high current DC output. The output bias from the TENG can be used to drive a Ti–Fe2O3/FeNiOOH based photoelectrochemical cell under sunlight to produce hydrogen. Moreover, under the situation without sunlight, the self‐powered system can be automatically switched to another working state to charge a Co3O4 based lithium‐ion battery. The hydrogen production rate reaches to 4.65 µL min‐1 under sunlight at the rotation speed of 120 rpm. The conversion efficiency of the whole system is calculated to be 2.29%. The system triggered by photoswitches can automatically switch between two working states with or without sunlight and convert the blue energy to either hydrogen energy or battery energy for easy storage and transmission, which widens the future applications for blue energy.

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Ion concentration in water is a key criterion for evaluating water quality. In this work, we developed a self-powered on-line ion concentration monitor in water transportation based on impedance matching effect of triboelectric nanogenerator (TENG). A rotary disc-shaped TENG (RD-TENG) and an ion concentration sensor were fabricated based on the industrial printed circuit board (PCB) technology.Flowing water in the pipeline acts as the energy source to drive the RD-TENG and generate an open-circuit (V oc ) of 210 V. The ion concentration sensor exhibits a nearly pure resistance characteristic under the alternating current (AC) signal with the frequency below 500 Hz, corresponding to the rotation speed of 250 rpm for the RD-TENG. The impedance matching relationship between the RD-TENG and ion concentration sensor are experimentally studied and applied to elucidate the sensing mechanism. Finally, a self-powered sensing system integrated with an alarm circuit was assembled which exhibits excellent responsibility and high sensitivity. The change of ion concentration with only 1×10 -5 mol/L can light up an alarm LED.

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Energy collection ways using solar energy, wave, wind, or mechanical energy have attracted widespread attention for small self-powered electronic devices with low power consumption, such as sensors, wearable devices, electronic skin, and implantable devices. Among them, triboelectric nanogenerator (TENG) operated by coupling effect of triboelectrification and electrostatic induction has gradually gained prominence due to its advantages such as low cost, lightweight, high degree of freedom in material selection, large power, and high applicability. The device with a single energy exchange mechanism is limited by its conversion efficiency and work environment and cannot achieve the maximum conversion of energy. Thus, this article reviews the research status of different types of hybrid generators based on TENG in recent years. Hybrid energy generators will improve the output performance though the integration of different energy exchange methods, which have an excellent application prospect. From the perspective of energy complementation, it can be divided into harvesting mechanical energy by various principles, combining with harvesters of other clean energy, and converting mechanical energy or various energy sources into hydrogen energy. For integrating multitype energy harvesters, mechanism of single device and structural design of integrated units for different application scenarios are summarized. The expanding energy harvesting efficiency of the hybrid TENG makes the scheme of self-charging unit to power intelligent mobile electronic feasible and has practical significance for the development of self-powered sensor network.