Delineating the Role of Vacancy Defects in Increasing Photocatalytic Hydrogen Production in an Amorphous Metal–Organic Framework Coordinated Graphitic Carbon Nitride

Abstract

The instability in aqueous solutions has impeded the effective employment of metal−organic frameworks (MOFs) for various photocatalytic applications. Recent literatures have proven that certain supports like graphitic carbon nitride (g-C 3 N 4 ) can improve the water stability and meet other functionalities responsible for photocatalytic water splitting. To expound on the mechanistic details central to the photoactivity of g-C 3 N 4 /MOF systems, we relate the activity of an amorphous nickel imidazole framework (aNi-MOF) with different vacancy (carbon and nitrogen) defects of engineered g-C 3 N 4 systems. Vacancy defects significantly alter the electronic structure and characteristics of photoexcited charge carriers and thus the photocatalytic activity of semiconductor photocatalysts. In this framework, by elucidation of both experimental and theoretical studies, carbon-defective g-C 3 N 4 with aNi-MOF (C v CN/aNi) proves to be a potential candidate to speed up the photocatalytic hydrogen evolution reaction. The results also potentially accord to the reactive interaction between g-C 3 N 4 and aNi-MOF that a Ni−N bond is vital in the photoactivity with the carbon-defective C v CN/aNi photocatalyst producing 3922.01 μmol g −1 for 3 h, which is 3900 and 1700 times better than those of pristine aNi-MOF and g-C 3 N 4 , respectively. Our report provides insight into correlating the reactive mechanism in a g-C 3 N 4 /MOF system and the role of defects in photocatalytic hydrogen evolution reactions.