Dual engineering of pores and surfaces in metal–organic frameworks via precision etching for enhanced photocatalytic performance

Abstract

The synthesis of metal–organic frameworks (MOFs) featuring hierarchical pores and tailored surface characteristics remains a great challenge. In this work, a mixed-ligand approach was employed to systematically examine the effects of post-synthetic conditions on the structural properties of MOFs. A new MOF, namely [Fe₃O(DMTDC)₃(TPT)Cl]·solvent (JOU-20), was synthesized for this investigation (H₂DMTDC = 3,4-dimethylthiophene-[2,3-b]thiophene-2,5-dicarboxylic acid; TPT = 2,4,6-tris(pyridin-4-yl)-1,3,5-triazine). Both experimental and theoretical analyses revealed that the difference in the stability of Fe–N and Fe–O bonds significantly influenced the pore structures and surface properties of the etched MOFs, thereby affecting their photocatalytic performance in the activation of peroxymonosulfate (PMS). Among them, a H₂O₂-treated MOF (labeled as JOU-20-H₄) with enlarged pore size, abundant open metal sites, and high hydrophilicity showed the highest photocatalytic activity. JOU-20-H₄/PMS system can effectively remove persistent organic pollutants from various types of aquatic environments even under sunlight. The JOU-20-H₄/PMS system degraded up to 95.6% of rhodamine 6G in 120 min with a rate constant of 0.026 min⁻¹, which was 5.2 times higher than that of the initial JOU-20. This work offers a novel approach to simultaneously adjust the pore and surface properties of MOFs, also guiding the construction of efficient photocatalysts for degrading organic pollutants.