Efficient Photocatalytic Degradation of p-Nitrophenol by Ag@Co-MOF Prepared Based on 1,3-Phenylenediacetic Acid

Abstract

Metal–organic frameworks (MOFs) are well-known for their promising applications in photocatalysis, but single-component MOFs have limited effectiveness in degrading organic pollutants. To address this, we designed a novel photocatalyst for the efficient degradation of p-nitrophenol (p-NP). In this study, we synthesized a two-dimensional [Co (tib)(mpda)(H₂O)₂]·H₂O (Co-MOF) (tib = 1,3,5-tris(1-imidazolyl)benzene, H₂mpda = 1,3-phenylenediacetic acid) using a hydrothermal method. Silver particles were then deposited on the surface of the Co-MOF via a photo-reduction method, forming Ag@Co-MOF. The incorporation of Ag particles accelerated photogenerated carrier transport and prevented the recombination of electrons (e⁻) and holes (h⁺), resulting in superior photocatalytic degradation performance. The bandgap energy of Co-MOF is 3.4 eV, whereas that of Ag@Co-MOF is reduced to 2.8 eV, significantly enhancing visible light absorption. After 240 min of illumination, Ag@Co-MOF achieved a degradation efficiency of 92.7% for p-NP, with a degradation rate of 0.0095 min⁻¹. Analysis of active substances and intermediates through free radical trapping tests, ESR tests, XPS valence band tests, and LC–MS revealed that Ag@Co-MOF promoted the generation of active substances ·OH and ·O₂⁻, facilitating the rapid oxidative degradation of p-NP. In summary, Ag@Co-MOF provides a promising and sustainable green pathway for pollutant removal and environmental remediation, while also expanding the application areas of MOF materials.