An electrochemical sensor for caffeic acid based on in-situ grown Co-MoO2@C/CNTs composite material

The development of efficient and sensitive electrochemical sensors for caffeic acid (CA) detection is critical for food safety and human health monitoring. However, conventional metal-organic framework (MOF) derivatives often suffer from particle agglomeration and limited electrical conductivity. Herein, we propose a novel in-situ growth strategy to construct a core-shell Co-MoO 2 @C composite, which is further integrated with multi-walled carbon nanotubes (CNTs) to achieve a “dispersive-supportive-catalytic” trifunctional sensing platform. Specifically, ZIF-67 was grown in situ on MoO 3 nanorods to form a core-shell MoO 3 @ZIF-67 precursor. Upon pyrolysis, this unique structure effectively prevented the agglomeration of Co nanoparticles and generated abundant Co-Mo-O active sites and heterojunction interfaces. The subsequent incorporation of CNTs not only constructed a highly conductive network but also significantly increased the electroactive surface area (3.65 mm 2 ) and adsorption capacity (1.744 nM·cm −2 ) via synergistic effects. The limit of detection (LOD) of the Co-MoO 2 @C/CNTs/GCE sensor for CA was 8.4 × 10 −10  M under the most suitable conditions. This work provides a new paradigm for designing MOF-oxide‑carbon ternary composites for advanced electrochemical sensing applications.