Integration of MOF-on-MOF-Derived Core-Shell CoFe@Fe₃Mo₃C with Graphene Oxide@Carbon Nanobubbles for Highly Selective...

Flutamide (Flu) is an antiandrogen drug associated with various side effects at high concentrations. A core-shell composite, MoG@ZIF-67@MIL-101, was synthesized through an in situ growth method using Mo-glycerate (MoG) solid spheres as the core and a MOF-on-MOF structure (ZIF-67@MIL-101) as the shell. After controlled carbonization, a CoFe bimetallic alloy nanoparticles @ metal carbide material (CoFe@Fe₃Mo₃C) with a unique core-shell structure was successfully obtained, in which strong electronic coupling was formed, exhibiting excellent electrocatalytic synergy. The successful construction of the MOF-on-MOF structure and the composite material was confirmed through various physical characterizations. Subsequently, the material was integrated with graphene oxide @ carbon nanobubbles (GO@CNB) to develop a CoFe@Fe₃Mo₃C/GO@CNB/GCE electrochemical sensor for Flu detection. Owing to the composite's outstanding conductivity and electrocatalytic activity, the sensor exhibited a wide linear range of 5.0 nm-10.0 µm and an ultralow detection limit of 3.4 nm. Density functional theory calculations showed that the composite possesses the strongest adsorption energy for Flu (-1.50 eV) and elucidated the electrochemical reaction mechanism. The sensor achieved recoveries of 96%-105% in water sample analysis, demonstrating its practical applicability. This study highlights the significant potential of integrating core-shell MOF-on-MOF-derived alloy carbide materials with 2D conductive carbon nanomaterials for environmental analysis.