Coordinative integration of amorphous nickel-imidazole framework with graphitic carbon nitride for enhanced photocatalytic hydrogen production

Herein, a new nickel metal-organic framework (Ni-MOF) was integrated with graphitic carbon nitride (g-C3N4) (prepared by polycondensation of different precursors, i.e., urea, thiourea and melamine) using the solvothermal method and used for the photocatalytic hydrogen production. Notably, crystalline Ni-MOF was unable to bond with g-C3N4 due to completely coordinated nickel sites in Ni-MOF, but amorphous Ni-MOF (aNi-MOF) successfully bonded with g-C3N4 owing to its uncoordinated nickel sites. The aNi-MOF incorporated with g-C3N4 (prepared by urea) exhibited hydrogen production of 2272.6 mu mol g-1 h-1 which was ~450, 4 and 7 times higher than aNi-MOF, thiourea and melamine derived g-C3N4 integrated with aNi-MOF, respectively. The substantial increment in photocatalytic activity can be attributed to the synergistic structural reconstruction of gC3N4/aNi-MOF in accordance with varying dangling amine groups, surface area and porosity offered by different precursors in formation of g-C3N4. Remarkably, the proposed work is the first report on the photocatalytic hydrogen production by an amorphous metal-organic framework and also an imidazole-based nickel framework. Thus, this work provides insight into the designing amorphous MOF- extended polymer heterostructure and will open up a new avenue to their catalytic performances.