Advances in Blue Energy Fuels: Harvesting Energy from Ocean for Self-Powered Electrolysis

70% of the earth's surface is covered by the ocean, and it represents a promising and renewable clean energy reservoir that waits for further exploration. Although hydrogen (H2) boasts a high energy density of 143 MJ kg-1 and environmentally friendly attributes, the widespread commercialization of green H2 production remains a formidable challenge. With huge amounts of water, the ocean presents an opportunity for generating H2 fuel through the process of seawater electrolysis. This review introduces ocean-driven, self-powered blue energy conversion devices, including triboelectric nanogenerators (TENGs), magnetoelastic generators (MEGs), and solar cells. They are able to convert renewable energy from the ocean, including water waves, wind, and solar energy, into electricity for on-site seawater-splitting and H2 generation. This review systematically reports this compelling approach by introducing the fundamental principles of the devices and showcasing the practical applications. Additionally, aiming to promote future research in the field of sustainable energy, this review also delves into the development of novel ocean energy harvesting systems with high energy conversion efficiency for large-scale and effective H2 production. Harvesting renewable energy from ocean in the forms of water waves, wind, and solar radiation is able to realize self-powered seawater-splitting and on-site hydrogen production, which could greatly contribute to mitigating energy crisis, net zero emissions, and carbon neutrality. image