2D/2d nanoconfined catalytic membrane for efficient water purification under photocatalysis-assisted peroxymonosulfate activation system

Abstract

Two-dimensional (2D) lamellar membranes offer excellent separation performance for organic pollutants; however, their broader application is limited by the permeability-selectivity trade-off, membrane fouling, and challenges in treating concentrated pollutants. Integrating membrane filtration with advanced oxidation processes (AOPs) is a promising approach to address these limitations. In this study, a porous 2D/2D nanoconfined catalytic membrane (CN@Co/Fe-MOF) was developed for the continuous removal of pollutants. Upon photoexcitation, the photogenerated electrons (e⁻) from g-C₃N₄ nanosheets were effectively separated and transferred to Co/Fe-MOF nanosheets, promoting the valence cycling of Fe/Co active sites and enhancing the peroxymonosulfate (PMS) activation to generate singlet oxygen (¹O₂). This system achieved the high-flux pollutant removal (70.41 L m⁻² h⁻¹), with the efficiencies of 98.7 % for rhodamine B, 99.11 % for evans blue, 96.83 % for methylene blue, 97.99 % for methyl orange, 98.3 % for acid orange G, and 89.78 % for tetracycline hydrochloride. Molecular dynamics (MD) simulations revealed rapid water transport through the layered porous hydrophilic structure, whereas density functional theory (DFT) calculations demonstrated that the nanoconfined channels thermodynamically facilitated spontaneous PMS dissociation at Co/Fe active sites. This work provides strategic insights into the design of heterogeneous catalytic systems and a mechanistic understanding of pollutant degradation under nanoconfinement.