Construction of B doped g-C3N4/Ni-MOF-74 porous heterojunction with boosted carrier separation for photocatalytic H2 generation

Novel heterojunction is favored to improve the separation of photogenerated carriers and maintain high redox ability. A porous heterojunction combining porous metal-organic frameworks (MOF), Ni-MOF-74, and porous B-doped g-C3N4 (BCN) was fabricated for solar-light-driven H2 generation. The permeable surface and type-I carrier transfer mode not only created more reactive sites for H2 generation but also facilitated mass transfer at the contact interphase among BCN and Ni-MOF-74 due to a slight difference in their valence bond energy, which enhanced the excellent light trapping ability and expanded spectral absorbance range and thus solving the intrinsic drawback of fast charge recombination of pristine g-C3N4. Besides that, B-doping enhanced redox ability and transport separation, and the BCN/Ni-MOF-74 composite demonstrated dramatically reduced hydrogen production overpotential. The optimal BCN-NM-3 showed outstanding H2 generation up to 2190 μmol g−1h−1, almost 11 times higher than BCN. The current study will benefit the development of new MOF-based photocatalysts and be influential in meeting environmental demands in the future.