N-doped CuFe-MOF-919 derivatives in activation of peroxymonosulfate for enhanced degradation of organic pollutants: 1O2 dominated non-radical pathway

Abstract

Metal organic framework (MOF)-derived carbon materials have received significant attention as catalysts for peroxymonosulfate (PMS)-mediated degradation of organic pollutants. Despite the growing interest, the challenge persists in designing MOF derivatives where non-radicals serve as the primary active species. This study introduces an N-doped carbon-based material denoted as CuFe@NC-10, featuring highly dispersed Cu and Fe bimetallic active sites. The design involves co-doping MOF-919(Fe) with melamine. Under identical experimental conditions, CuFe@NC-10 exhibited remarkable performance, degrading 99.5 % of Rhodamine B (RhB) within 30 min, with a mineralization rate of 60 %. Notably, the pseudo-primary kinetic constant was 5.8 times higher than that observed for the pure MOF derivative (CuFe@NC). CuFe@NC-10 displayed consistent activation capacity across a broad pH range, and its catalytic performance remained largely unaffected by the coexistence of inorganic anions and humic acid. Quenching experiments and electron paramagnetic resonance (EPR) analysis indicated that singlet oxygen (1O2) primarily drove RhB degradation. X-ray photoelectron spectroscopy (XPS) findings suggested that the valence transition between Cu and Fe facilitated 1O2 generation, confirming PMS as the primary source of 1O2. The RhB degradation pathway was deduced through Q Exactive mass spectrometer and density-functional theory (DFT) calculations. Additionally, the study evaluated the ecotoxicity of RhB and its intermediates, providing essential insights into ecological risks associated with its degradation.