Surface and morphology modulated adsorption-activation of trace concentration hydrogen peroxide with multiple electron transfer pathways and sustained Fenton reactions
Zhiqun Xie, Fan Li, Carolina Belver, Wen Liu, Yanan Shang, Shuang Luo, Zongsu Wei
Abstract
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