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

Abstract

To promote mass transfer and activation of hydrogen peroxide (H2O2) in Fenton-like reactions, a novel MOFs-derived Fe2O3 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 Ca2+ and Mg2+ modulated the growth of crystal clusters to prevent aggregation of Fe2O3 nanoparticles and provide more reaction sites. Likewise, the abundant acid sites (–SO3H) promote the chemisorption of even trace-concentration H2O2 (S–O bonding), whereas the S–Fe bonding accelerates electron transfer to promote the Fe3+/Fe2+ cycle and thus the H2O2 utilization. More interestingly, surface-adsorbed H2O is found to be activated to form •OH, due to electron-poor Fe sites formed after detachment of –SO3H, 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 H2O2 and even H2O in Fenton-like systems.