Integration of MOF‐on‐MOF‐Derived Core–Shell CoFe@Fe ₃ Mo ₃ C with Graphene Oxide@Carbon Nanobubbles for Highly Selective Detection of Flutamide

ABSTRACT 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@Fe ₃ Mo ₃ C) 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@Fe ₃ Mo ₃ C/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 n m –10.0 µ m and an ultralow detection limit of 3.4 n m . 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.