Enhancing effect of dual-atom catalysts on tetrabromobisphenol S degradation via peroxydisulfate activation: Synergism of Fe-Cu and electron-transfer mechanism

Increasing the metal atom loading on single-atom catalysts may not improve their activation performance on peroxydisulfate (PDS). In this study, dual-atom catalysts (Fe0.4Cu0.6-N-C) were synthesized using a one-pot method: Fe and Cu atoms were uniformly dispersed as dual Fe-Cu atom pairs in a nitrogen-doped graphitic carbon support. Fe0.4Cu0.6-N-C exhibited an excellent degradation efficiency (98.7 %) and rate (0.060 min-1) for tetrabromobisphenol S (TBBPS, 5 mg/L) within 60 min of treatment under optimized conditions. In-situ Raman spectroscopy, electrochemical analyses, and electron paramagnetic resonance tests revealed that elec-tron transfer was the main degradation pathway for TBBPS. Density functional theory calculations demonstrated that the synergism between Fe and Cu atoms enhanced the adsorption of PDS and the dual Fe-Cu sites served as the active centers during PDS activation. Additionally, the TBBPS degradation pathways were investigated, and most of the TBBPS intermediates were considered innocuous. These findings give weight to the enhanced effect of the synergism of dual Fe-Cu sites on PDS activation, providing an innovative system for pollutant degradation through electron-transfer pathways.