Dual Role of Missing-Linker Defects Terminated by Acetate Ligands in a Zirconium-Based MOF in Promoting Photocatalytic Hydrogen Peroxide Production

Defect engineering for metal–organic frameworks is a promising process that can modulate their electronic structure, surface chemical properties, and porosity. In this study, we demonstrate that defect engineering using an acetic acid modulator on a zirconium-based metal–organic framework (UiO-66-NH2) is an effective approach to enhance the photocatalytic performance in hydrogen peroxide (H2O2) production. The amount of missing-linker defects introduced into the UiO-66-NH2 structure was varied by changing the acetic acid concentration. A higher H2O2 concentration was produced when defective UiO-66-NH2 was used under light irradiation compared with pristine UiO-66-NH2. It was demonstrated that the efficient excited carrier consumption during the photocatalytic reaction originated from promoting the linker-to-cluster charge transfer (LCCT) process, and the suppression of H2O2 decomposition was due to hydrophobization of the samples by introducing missing-linker defects with acetate ligands. This study provides new insight into design strategies for developing MOF photocatalysts with different electronic structures and hydrophobicity by introducing missing-linker defects.