Triboelectric nanogenerators for underwater energy harvesting and self-powered sensing

Smart ocean systems require underwater sensing networks capable of long-term autonomous operation, low maintenance, and distributed deployment. However, existing nodes remain limited by insufficient power supply, strong environmental interference, and difficult in situ maintenance. Owing to their high efficiency in low-frequency mechanical energy conversion, broad material compatibility, and flexible structural design, triboelectric nanogenerators provide a promising route for underwater energy harvesting and self-powered sensing. This review systematically summarizes recent progress in TENG-based underwater energy harvesting and self-powered sensing. First, the fundamental mechanisms such as contact electrification are discussed, with particular emphasis on the critical roles of encapsulation isolation in stabilizing device output in marine environments. Subsequently, TENG-based ocean current energy harvesting strategies are reviewed, including rigid structures, flexible structures, bioinspired configurations, and large-scale arrayed and networked systems. In addition, representative underwater self-powered sensing applications are summarized, including ocean current velocity sensing, distributed disturbance sensing, and artificial lateral-line sensing. Finally, key challenges are discussed in such as terms of long-term deep-sea durability, and intelligent energy management. Future perspectives are proposed toward the integration of advanced materials, fluid-structure interaction-guided design, and marine blue-energy networks, aiming to promote the transition of TENG-based underwater systems from laboratory demonstrations to long-term ocean deployment.