Ocean-Based Triboelectric Nanogenerators: A Defect Engineering Approach on Efficacious Electrodes and Dielectric Materials

Marine energies, as renewable resources, offer substantial potential for large-scale energy harvesting. In recent years, triboelectric nanogenerators (TENGs) have emerged as a promising technology for applications in energy harvesting, self-powered sensing, control, and instrumentation. This interest is driven by their lightweight, cost-effective design, reasonable efficiency at low frequencies, and simple structure. TENGs have also shown considerable technical advantages in efficiently harvesting low-frequency ocean wave energy. This paper provides a systematic review of the latest developments in ocean energy harvesting with TENGs, analyzing the principles, structures, efficiencies, and performances of various TENG systems. We highlight current challenges and future trends in TENG applications for ocean energy collection. Our overview discusses the significance and mechanisms of energy harvesting using TENGs and explores the classification of optimal electrode materials, emphasizing composite materials for their advantageous effects on triboelectric properties. Additionally, we introduce new defect engineering approaches to enhance TENG performance and examine hybrid systems that integrate piezoelectric and triboelectric concepts. Finally, we address the significant challenges in selecting triboelectric materials, which must be overcome to advance research and development. This review aims to guide the selection and assembly of innovative electrode materials for emerging clean energy sources, with defect characterization tools clarifying the structure-efficiency relationship to support the development of novel materials for future clean water energy solutions.