High Energy Density Non‐Contact Bidirectional Spinning Oscillating Float‐Type Triboelectric Nanogenerators for Energy Extraction From Irregular Waves

Abstract The pursuit of sustainable and self‐sufficient energy solutions has become critical for the advancement of marine Internet of Things (IoT) technologies. While triboelectric nanogenerators (TENGs) have shown great potential in harnessing high‐entropy, low‐frequency wave energy, their practical applications are hindered by low power output and issues related to frictional wear. Hence, this research presents a novel non‐contact bidirectional spinning oscillating float‐type triboelectric nanogenerator (OF‐TENG) for efficient wave energy harvesting. Utilizing a planetary gear and bidirectional rotation structural design, low‐frequency vertical wave energy with random and multi‐directional conditions can be converted into high‐frequency rotational energy. At a frequency of 0.5 Hz, the OF‐TENG achieves a peak output power of 93.48 mW, and an average output volumetric power density of 31.3 W m⁻ 3 . Furthermore, the non‐contact working mode ensures robust output stability, with no significant performance degradation observed after 5,680,000 working cycles. An intelligent self‐powered marine ranching system for automatic feeding and water quality monitoring is further developed based on the OF‐TENG. This work not only provides an effective solution for harvesting low‐frequency wave energy, but also promotes the development of smart marine IoT technologies and marine agriculture.