Recyclable Molecular Ferroelectrics to Harvest Mechanical Energy for Sustained Hydrogen Generation

Production of hydrogen fuel from water and renewable energy offers one of the most promising pathways for carbon neutrality and sustainable development. However, existing hydrogen generation technologies struggle with durability issues, such as poisoning, coking, and fouling, so it is a crucial economic concern to find a long-term hydrogen generation catalyst or approach. Herein, we report a recyclable cyclic supersaturation strategy harnessing molecular ferroelectric (TMFM)_0.26(TMCM)_0.74CdCl₃ (MF-1) for hydrogen generation, which enables cycles of recrystallization and dissolution of molecular ferroelectric nanocrystals in supersaturated aqueous solution systems. The molecular ferroelectric nanocrystals generate hydrogen through the piezoelectric effect and dissolve in aqueous solution, enabling complete hydrogen desorption. Additionally, their low acoustic impedance, closely matching that of water, facilitates efficient mechanical energy transmission, thereby enhancing hydrogen generation efficiency. We achieve a robust hydrogen generation rate of record-high 11.56 mmol g^-1 h^-1 (mechanical-to-hydrogen energy conversion efficiency of 35.6%), with outstanding durability surpassing 1500 h. This work not only provides a new strategy for efficient and sustainable hydrogen generation but also boosts the outlook for the application of water-soluble molecular ferroelectric materials.