Effect of the Defect Modulator and Ligand Length of Metal–Organic Frameworks on Carbon Dioxide Photoreduction

Abstract

The nature of defects and organic ligands can fine-tune the absorption energy (E abs) of metal–organic frameworks (MOFs), which is crucial for photocatalytic reactions; however, the relevant studies are in their infancy. Herein, a series of typical MOFs of the UiO family (UiO-6x-NH2, x = 8, 7, and 6) with ligands of varied lengths and amino-group-modified defects were synthesized and employed to explore their performance for photocatalytic CO2 reduction. Sample UiO-66-NH2-2ABA (2ABA = 3,5-diamino-benzoate) with the shortest dicarboxylate ligand and two amino-group-modified defects exhibits superior photocatalytic activity due to the lowest E abs. The CO yield photocatalyzed by UiO-66-NH2-2ABA is 17.5 μmol g–1 h–1, which is 2.4 times that of UiO-68-NH2-BA (BA = benzoate) with the longest ligand and no amino group involved in the defects. Both the experiments and theoretical calculations show that shorter dicarboxylate ligands and more amino groups result in smaller E abs, which is favorable for photocatalytic reactions. This study provides new insights into boosting the photocatalytic efficiency by modulating the defects and ligands in MOFs.

Pillar-Layered Metal-Organic Frameworks for Sensing Specific Amino Acid and Photocatalyzing Rhodamine B Degradation

“…The red-shift and enhancement of the emission in 1 is probably caused by the coordination between the Cd(II) and NTB 3− to increase the rigidity of the framework [ 38 ]. In addition, DPA shows negligible luminescence, which may be caused by the intramolecular resonance energy transfer (RET) and inner filter effect (IFE) due to presence of amino group [ 39 , 40 ]. To explore the influence of solvent on emission of 1 [ 41 ], PL spectra of 1 after immerging in varied solvent of DMF, EtOH, IPA, DMA, CH 3 CN, MeOH, toluene, DCM and H 2 O were recorded.…”

Tailoring defect-type and ligand-vacancies in Zr(iv) frameworks for CO2 photoreduction

“…42,43 Besides, the Zr 3d peaks of defect UiO-66-NH 2 -ML-100 shift to a lower binding energy compared to those of other defect MOFs as well as the pristine one, implying that it is easier to generate Zr 3+ due to the improvable efficiency of electron transfer. 44,45 Hence, UiO-66-NH 2 -ML-100 of ML nature with ligand-vacancy defects may benefit the photocatalytic reaction.…”

Cationic Ni-MOF-Assembled CdS/PFC-8 Catalyst for Photocatalytic Hydrogen Production with Selective Benzyl Alcohol Oxidation under Visible Light

“…The CdS has a flat band potential of −0.92 V vs. Ag/AgCl, with a positive slope (Fig. S3a); which indicates an n-type semiconductor 38,39 . And the PFC-8 has a flat band potential of −0.40 V vs. Ag/AgCl (Fig.…”