Tuning Electronic\nand Proton Transfer Properties on\nAmino-Functionalized Co-Based MOF for Efficient Photocatalytic Hydrogen\nEvolution

Efficient hydrogen (H<sub>2</sub>) production through\nphotocatalytic\nwater splitting was achieved by using an amino-functionalized azolate/cobalt-based\nmetal–organic framework (MOF). While previous reports highlighted\nthe amino group’s role only as a substituent group for enabling\nlight absorption of MOFs in the visible region, our present study\nrevealed its dual role. The amino substituent not only acts as an\nelectron donor to increase the electron availability at the active\nCo sites but also provides hydrogen-hopping sites within the pore\nchannel, facilitating proton (H<sup>+</sup>) diffusion along the framework.\nThis dual functionality significantly boosts the performance of this\nCo-MOF as a hydrogen evolution cocatalyst. When combined with fluorescein\nand triethylamine as the photosensitizer and sacrificial agent, respectively,\nthe Co-MOF achieved a remarkable H<sub>2</sub> production rate of\n27 mmol g<sup>–1</sup> over 4 h. Notably, this performance\nsurpasses those of benchmark platinum (Pt) and titanium dioxide (TiO<sub>2</sub>) cocatalysts.