Ultrafine metal-organic framework @ graphitic carbon with MoS-CNTs nanocomposites as carbon-based electrochemical sensor for ultrasensitive detection of catechin in beverages.

GO/Co-MOF/PPy-350 (GPC-350) was synthesized by in situ growth of ultrafine Co-MOF on graphene oxide (GO), followed by encapsulation with polypyrrole (PPy) and calcination at 350.0℃. Meanwhile, MoS-MWCNTs (MoS-CNTs) were produced via the in situ synthesis of MoS within multi-walled carbon nanotubes (MWCNTs). The electrochemically superior GPC-350/MoS-CNTs nanocomposite was then achieved by combining GPC-350 with MoS-CNTs. The polypyrrole encapsulation serves to protect the ultrafine Co-MOF, preventing its degradation during the calcination process. The linear detection range of the GPC-350/MoS-CNTs/GCE sensor for the determination of catechin (CA) in phosphate buffered saline (PBS) was from 5.0 to 1800.0 nM with a limit of detection of 1.78 nM. In addition, the materials were characterized using SEM, EDX, TEM, XRD, EIS, XPS, FTIR, and Raman. These results indicate that the synthesis of GPC-350/MoS-CNTs nanocomposites is successful and CA in beverages samples can be effectively detected using electrochemical sensors. Additionally, the reaction mechanism of CA was explored through cyclic voltammetry. The application of GPC-350/MoS-CNTs nanocomposites in sensor technology offers innovative approaches for the ultrasensitive detection of flavonoids.