Hierarchical synthesis of binary ZnO@MWCNTs heterogeneous photocatalyst derived from porous Zn metal organic framework (MOF) template: Study on the effective photodegradation of Congo red (CR) dye

Abstract

This study presents the synthesis of a heterogeneous ZnO@MWCNTs photocatalyst through a solvothermal method, employing a Zn-metal organic framework (MOF) template. The resulting nanocomposite showcases ZnO nanorods integrated with MWCNTs, forming a material characterized by nanosized building blocks, a substantial specific surface area, robust pore structure, and uniform morphology. A comprehensive XRD characterization reveals crystalline ZnO nanorods proficiently loaded onto the MWCNTs surface, forming a cohesive nano-composite. The inclusion of MWCNTs influences crystal growth, reducing crystallite size and altering optical absorption due to surface Plasmon resonance. This leads to a higher concentration of surface hydroxyl groups in the ZnO framework. Additionally, MWCNTs act as electron sinks, significantly reducing ZnO photooxidation and enhancing overall photostability in the composite. The photocatalytic efficacy of the composite in Congo Red (CR) degradation is impressive, achieving 92% degradation within 90 min of UV light exposure. A proposed photocatalytic mechanism elucidates the heightened performance of the synthesized photocatalysts. Notably, the MOF-derived ZnO@MWCNTs exhibited superior dye adsorption capacity compared to alternative adsorbents. This work underscores the immense potential of the ZnO@MWCNTs nanocomposite as a highly efficient photocatalyst for environmental remediation, offering significant advancements in dye degradation and wastewater treatment technologies.