Interfacial hydrothermal synthesis of Cu@Cu2O core-shell microspheres with enhanced, visible-light-driven photocatalytic activity

In this study, core-shell Cu@Cu₂O microspheres were synthesized with an interfacial hydrothermal method. The resulting products were systematically characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. A core-shell Cu@Cu₂O microsphere formation mechanism, which involved the in situ transformation of Cu to Cu₂O, was proposed on the basis of the characterization results. That is, pure Cu microspheres were first formed through the reduction of copper(II) acetylacetonate. Then surface Cu was oxidatively transformed to a Cu₂O shell, resulting in the Cu@Cu₂O core-shell structure. The content of Cu₂O shell in the composite microspheres increased with prolonged reaction time. The as-prepared Cu@Cu₂O core-shell microspheres exhibited enhanced photocatalytic activity as compared to Cu₂O on the degradation of gaseous nitrogen monoxide under visible light irradiation. The reasons for visible-light-driven photocatalytic activity enhancement on Cu@Cu₂O core-shell microspheres were discussed. These Cu@Cu₂O microspheres are ideal candidates for fundamental studies as well as catalytic, electronic, and magnetic applications. © 2009 American Chemical Society.