Porous ZnO–ZnSe nanocomposites for visible light photocatalysis

Abstract

We report the synthesis of porous ZnO–ZnSe nanocomposites for use in visible light photocatalysis. Porous ZnO nanostructures were synthesized by a microwave-assisted hydrothermal reaction then converted into porous ZnO–ZnSe nanocomposites by a microwave-assisted dissolution–recrystallization process using an aqueous solution containing selenium ions. ZnO and ZnSe nanocrystallites of the nanocomposites were well-mixed (rather than forming simple core–shell (ZnO–ZnSe) structures), particularly, in the outer regions. Both ZnO and ZnSe were present at the surface and exposed to the environment. The porous ZnO–ZnSe nanocomposites showed absorption bands in the visible region as well as in the UV region. The porous ZnO–ZnSe nanocomposites had much higher activities than the porous ZnO nanostructures. Control experiments using cutoff filters revealed that the main photocatalytic activity of the synthesized nanostructures arose from photo-excitation of the semiconductor (ZnO or ZnSe) via absorption of light of an energy equal to or exceeding the band gap energy.