Nanogenerators via dynamic regulation of electrical double layer

The world is grappling with dual crises of energy depletion and environmental degradation, as escalating global energy demands strain the sustainability of existing systems. While traditional energy harvesting technologies such as wind, solar, and hydropower have progressed, challenges in energy storage and system stability persist, underscoring the urgent need for more efficient and sustainable alternatives. Emerging water-based energy harvesting technologies that harness the dynamic regulation of electrical double layers (EDLs) at solid-liquid interfaces offer significant advantages, including enhanced energy conversion efficiency and flexible application potential. These systems are particularly well-suited to meet the growing demand for distributed energy in the Internet of Things (IoT), where adaptable and scalable energy solutions are essential. Key nanogenerator technologies utilizing dynamic EDL regulation are classified into five major types: solid-liquid triboelectric nanogenerators (S-L TENGs), triboiontronic nanogenerators (TINGs), hydrovoltaic technology, moisture-enabled electric generators (MEGs), and osmotic power sources. This review provides a comprehensive analysis of their operating principles, output characteristics, and typical applications. Furthermore, it addresses the main challenges and bottlenecks these technologies face and outlines future research and development opportunities, advancing the field of water-based energy harvesting.