Defect-rich UiO-66@g-C3N4/Ni frameworks as efficient water splitting photocatalysts

Abstract

In this report, we uncover the synergistic role of g-C₃N₄, a cocatalyst (Ni), and defect sites of Zr-MOFs for unprecedented hydrogen evolution activity. Further, the interaction between defect rich UiO-66-D and g-C₃N₄ is well-supported by theoretical understanding and photocatalysis trends. The key role in the enhanced activity is further substantiated by considering the abundant type-II heterojunction between UiO-66-D and g-C₃N₄ in the hybrid composite. This study emphasizes the significance of defect-induced local strain and modification of the electronic structure at the junction connecting UiO-66 and g-C₃N₄ along with Ni NPs, demonstrating their role in the catalytic activity. Ligand oriented defect engineering is deliberately utilized to manipulate photonic and electrical attributes of the UiO-66 framework. Improved catalytic performance is ascribed to structural stabilization of the composite by the introduction of unsaturation in UiO-66 and suitable coordinated Ni NPs over g-C₃N₄, resulting in a multi-fold enhancement of the hydrogen production rate of 2.6 mmol g⁻¹ h⁻¹ with an AQY of 6.41% at 420 nm as compared to the pristine material.