P-N Junction Catalysis in Action: Boosting Norfloxacin Photodegradation with ZIF-67-based Co3O4 Wrapped in MoS2 with Surface Functionalized Graphene Quantum-Dot

The primary challenge in photocatalytic application is to address the inefficiency in exploiting the photo-induced charge carriers. The dynamic behaviors of photogenerated carriers can be controlled through an internal electric field by building a p -n heterojunction. In this respect, p -n heterojunctions constructed from zeolitic imidazolate frameworks (ZIFs) with further surface functionalization are uniquely active and can increase the charge separation due to a favorable band structure. Thus, the present work demonstrates the preparation of an excellent visible -light absorbing photocatalyst based on a Co3O4 from ZIF -67 wrapped with MoS2 and functionalized with graphene quantum dots (GQDs), which is evaluated for the photodegradation of norfloxacin. Under visible light irradiation, the as-designed GQDs-functionalized MoS2@Co3O4 p -n heterojunction photocatalyst outperforms the individual MoS2 and Co3O4 semiconductors. The remarkable degradation efficiency is mostly due to the formation of a p -n heterojunction between MoS2 and the ZIF-67-based Co3O4. The photocatalytic mechanism of the as-designed system is deduced from reactive species trapping studies. This study sheds light on the design of a photocatalytic system based on ZIF -67, and on the effect of surface functionalization, thereby expanding the potential practical application of these materials in the field of environmental remediation.