Direct Current Triboelectric Nanogenerator Based on Contact Electrification, Air Breakdown, Electrostatic Induction, and Charge Leakage for Self‐powered Applications

Abstract Diverging from air breakdown‐based triboelectric nanogenerators (TENGs), recent TENG designs present high output power density without requiring precise control over discharge channels. However, existing researches predominantly ascribe its direct current output to electrostatic induction, disregarding the critical factor of charge leakage. This oversight hampers efforts to improve device performance, especially in material selection and optimization. Here, the generation of direct current signals ultimately stems from material charge leakage and spatial electrostatic induction is illustrated. Through theoretical analysis, visualization, and experimental measurement of four phenomena in the device, a quadruple‐effect mechanoelectrical conversion mechanism is established to refine the material selection rule. Under this guideline, the output power density is increased by 34.42% in contrast to the electrostatic induction direct current TENG. For practical applications, a power management circuit is utilized to boost the device's charging rate by up to 18 times. Furthermore, the high voltage of the device can activate discharge‐type UV tubes, demonstrating great potential in developing self‐powered wastewater treatment systems. The multiple charge behaviors proposed in this work, along with the material selection rule, lay a solid foundation for achieving high output power density in direct current TENGs.