Synthesis of CoxZn1-x zeolitic imidazolate frameworks (ZIFs) as efficient photocatalyst with high stability

Abstract

Sodalite-topology zeolitic imidazolate framework-8 (ZIF-8) composed of Zn2+ ions and organic linkers exhibit excellent physical and chemical properties such as high porosity, large surface area and abundant active sites. While it can only be excited by UV light due to the wide bandgap energy, which limits its application in photocatalysis. Herein, we synthesized Co-doped ZIF-8 with various ratio and systematically investigated its promotion effects on photocatalytic reaction. The as-synthesized CoxZn1-x-ZIF possessed homogeneous dodecahedron crystals and developed porous structure, together with obvious light absorption in visible frequency range. The photocatalytic performance of methylene blue (MB) had been improved with increasing of Co2+/Zn2+ ratio in ZIFs, while the reaction stability of Co0.75Zn0.25-ZIF and Co1.0-ZIF significantly decreased due to the apparent collapse in crystal phase. Taken together, Co0.5Zn0.5-ZIF was demonstrated to be a remarkable photocatalyst with high photocatalytic activity and strong stability. The photogenerated ·O2− and ·OH radicals were found to react as main oxygen species in photocatalytic reaction.

Keywords

• Metal-organic framework
• CoxZn1-x-ZIF
• Photocatalyst
• Reaction kinetics
• Stability