Copper Foam-Supported CuxO@Fe2O3 Core–Shell Nanotubes: An Efficient Ozonation Catalyst for Degradation of Organic Pollutants

Copper foam (CF)-supported CuxO@Fe2O3 core–shell nanotubes (CF/CuxO@Fe2O3 NTs) were synthesized as a hybrid catalyst for heterogeneous catalytic ozonation (HCO). The hybrid catalyst exhibits high activity and excellent stability for the HCO of organic pollutants. The total organic carbon removal rates of methyl orange, ibuprofen, and nitrobenzene via HCO were 89, 82, and 88%, respectively, which are over 2 times higher than the corresponding values obtained without the catalyst. The hybrid catalyst also displays wide pH operation range, low metal leaching, easy separation from treated water, and excellent recyclability. We prove that large amounts of Lewis acid sites with medium acidity are created at the CuxO/Fe2O3 interface due to the synergic effect of CuxO and Fe2O3. These medium acid sites are the main active centers for the production of free hydroxyl radicals (•OH) and superoxide radicals (O2•– or HO2•) in neutral solution. Moreover, the 3D porous framework of the catalyst enables easy dispersion in and separation from water. This work develops a new strategy to design HCO catalysts by combining strong and weak Lewis acid oxides and also opens a new avenue for developing HCO catalysts on a 3D porous framework.