Femtosecond laser processing of metal-oxide nanostructures for flexible photo-electrochemical cell

Due to more advantageous than rigid electronics in terms of productivity and another possibility for new research field, flexible photo-electrochemical (PEC) water-splitting cells have huge potential. However, photo-electrochemically instability of current collector under harsh aqueous electrolyte condition and high-temperature post-annealing of transition metal-oxide based photoanodes are limited in making a flexible PEC water-splitting cells. Here, we report a novel approach to make a flexible thin-film PEC water-splitting cell by using femtosecond laser processing techniques. Using direct laser writing carbonization and femtosecond laser crystalline phase transformation, the fabricated flexible thin-film photoanode demonstrated strong PEC performance. Moreover, it exhibited outstanding mechanical durability, even under extreme bending conditions. Thanks to its robust mechanical properties, the flexible thin-film photoanode enables space-efficient hydrogen harvesting by forming a volume-reduction structure.