Engineered nanoconfinement activates Fenton catalyst at neutral pH: Mechanism and kinetics study

Abstract

We proposed to establish nanoscale spatially confined Fenton treatment architectures to overcome the catalyst deactivation issue frequently seen at neutral pH. We demonstrated this idea by growing four typical iron oxide catalysts (Fe3O4, FeOOH, CuFe2O4, and FeOCl), respectively inside the nanochannels of anodized aluminum oxide scaffold, wherein the confined space (≈5 nm) significantly accelerated heterogeneous Fenton treatment of organic pollutants, with up to 310 times kinetics enhancement under normalized surface area compared to the counterpart bulk reactions with suspension catalysts. Based on experimental and computational studies, we gained the mechanistic details on how did the nanoconfinement enhanced the protonation of surfaces driving the catalysis, and showed how much of its significance over other influencing factors on enhancing the treatment kinetics and a sustained catalysis. Our findings mark an important advance on developing nanoconfined Fenton treatment systems that enable efficient catalyst activation and maximal treatment kinetics, without additional chemicals or electro-/photo-energies.