Waste Eggshell-Derived Dual-Functional CuO/ZnO/Eggshell Nanocomposites: (Photo)catalytic Reduction and Bacterial Inactivation

Transforming biological waste into high value-added materials is of significant importance to environmental protection and sustainable development of economy. Eggshell as a type of naturally occurring organic-inorganic biomaterials featuring a unique hierarchically porous structure has been widely investigated in the fields of catalysis and adsorption, as well as energy. Herein, CuO/ZnO/eggshell (CZ/ES) composites were rationally fabricated by using waste eggshell as a template. After a simple deposition and calcination process, the CuO and ZnO nanoparticles were evenly distributed over the surface of the CaCO3. The (photo)catalytic activity and antibacterial properties of the nanocomposites were subsequently investigated. The results showed that the CZ/ES nanocomposite exhibited a superior catalytic reduction and antibacterial activity. The catalytic reduction reaction rate constant K-app of 4-nitrophenol under the irradiation of UV-vis light was calculated to be approximately five times higher than that obtained in the absence of light irradiation. Besides, the CZ/ES nanocomposite exhibited significant antibacterial property for the destruction of E. coli and S. aureus. The enhanced performance in the (photo)catalytic reduction of 4-nitrophenol and bacterial disinfection of CZ/ES may be attributed to the strong reactant absorbance capacity, large amounts of reaction sites, and improved separation efficiency of the electrons. Furthermore, the reaction mechanism of the catalytic reduction of 4-nitrophenol was also discussed in detail.