Surface and morphology modulated adsorption-activation of trace concentration hydrogen peroxide with multiple electron transfer pathways and sustained Fenton reactions

To promote mass transfer and activation of hydrogen peroxide (H 2 O 2 ) in Fenton-like reactions, a novel MOFs-derived Fe 2 O 3 was tailor-designed through surface sulfur modification and morphology tuning for degrading a group of persistent micropollutants, i.e. , sulfamethoxazole, enrofloxacin, and ofloxacin. The introduction of Ca 2+ and Mg 2+ modulated the growth of crystal clusters to prevent aggregation of Fe 2 O 3 nanoparticles and provide more reaction sites. Likewise, the abundant acid sites (–SO 3 H) promote the chemisorption of even trace-concentration H 2 O 2 (S–O bonding), whereas the S–Fe bonding accelerates electron transfer to promote the Fe 3+ /Fe 2+ cycle and thus the H 2 O 2 utilization. More interestingly, surface-adsorbed H 2 O is found to be activated to form • OH, due to electron-poor Fe sites formed after detachment of –SO 3 H, demonstrating a sustained radical yield for the micropollutant degradation. This study opens new perspectives in catalyst design to ultimately realize the utilization of trace-concentration H 2 O 2 and even H 2 O in Fenton-like systems. • Ca 2+ /Mg 2+ modulated MOF structure avoids Fe 2 O 3 aggregation for more reaction sites • Sulfur modification promotes e - transfer via Fe-S bond for activating trace H 2 O 2 • Sulfite groups improve the affinity for H 2 O 2 and induce the formation of SO 4 • - • Electron-poor Fe activates surface H 2 O to produce • OH for sustained Fenton reaction