Reverse loading of inert Al2O3 onto active iron oxide for improved H2O2 activation and pollutant degradation

Developing heterogeneous iron-based catalysts with superior reactivity and stability is a long-term goal for hydrogen peroxide (H2O2) activation in Fenton-like technique for water remediation. Supported iron-based nanocomposites are of great interest due to their earth abundance, environmental friendliness, and tunable structure. However, existing iron-based Fenton catalysts are normally designed via the loading of iron-derived nanoparticles onto various inert substrates, where the surface reactive sites are hardly affected by the substrate. Here, we report the first example of reversely loaded FeOx-Al2O3 nanocomposite via overturning the loading direction, i.e., loading inert Al2O3 support onto reactive FeOx nanoparticles. The resultant FeOx@Al2O3-R catalyst demonstrated much improved reactivity for H2O2 activation and bisphenol A removal (by 14 times in terms of first-order rate constant) than its analog FeOx/Al2O3-T, which was prepared via the loading of FeOx nanoparticles onto inert Al2O3 support. Moreover, FeOx@Al2O3-R exhibited excellent stability with Fe leaching only one sixth of FeOx/Al2O3-T. Systematic characterization results revealed that the inert Al ions modify the electronic environment and properties of the surface Fe reactive sites. This work provides an alternative reverse loading strategy to traditional loading method for the preparation of iron-based nanocomposite catalyst that is highly efficient for H2O2 activation and pollutant removal.