Recent Advances towards Ocean Energy Harvesting and Self-Powered Applications Based on Triboelectric Nanogenerators

Ocean contain abundant clean energies including tidal and wave, but such energies are known for low frequency and large excitation amplitude, posing considerable challenges for high-efficiency energy conversion. As an emerging technology, triboelectric nanogenerators (TENGs) have been widely used in energy harvesting and novel sensor design due to their high sensitivity and flexible structure. Meanwhile, they show great advantages in the low-frequency environment (<5 Hz), and display great potential for deployment in remote ocean waters, and construction of large-scale TENG networks. In this review, firstly, the working principle of TENGs and various configurations developed for the marine environment are introduced, which mainly include solid-solid and solid-liquid interfaces. Then, from the viewpoint of power improvement, authors are most concerned about the modification methods of materials such as surface modification, electron injection, and chemical doping. Meanwhile, improved technologies for energy harvesters in marine environment are discussed in detail, such as improving the hydrophobicity and degradation of materials, studying the self-healing ability of materials, and designing power management circuits. Finally, the current challenges are summarized, and research trends are given from both short-term and long-term perspectives.