Publication

Abstract : Hydrogen is a promising clean energy carrier, but efficient production from seawater remains challenging due to the passivating Al2O3 layer on aluminium. In this study, five GaInSnBi liquid metal alloys compositions are synthesized and dip-coated onto aluminium rods to overcome this limitation, enabling spontaneous hydrogen generation from seawater under ambient conditions. Among the tested compositions, Ga60In10Sn25Bi5 achieves near-theoretical hydrogen yield with high hydrogen purity. The introduction of a dilute ionic liquid further enhances the reaction rate to 1200 mL g−1 within 150 s and reduces the apparent activation energy to 28.2 kJ mol−1. In parallel, the process modifies seawater properties and significantly reduces fluoride content during hydrolysis, with fluoride concentrations brought below detection limit by subsequent filtration using aluminium hydroxide by-products. The liquid metal alloy can be recovered with a yield of approximately 95%, demonstrating short-term recyclability. Scale-up experiments using 5 g of coated aluminium produce 6.87 L of hydrogen in 210 s illustrating the potential of this approach as an on-demand hydrogen source for future proton exchange membrane fuel cell applications, while highlighting the need for further long-term, device-level, and techno-economic studies.