Rational Design of Bimetallic MOF‐Derived Cu/Co@N‐C Nanocubes for Ultrasensitive Electrochemical Nitrite Detection

A facile coprecipitation‐pyrolysis strategy was employed to fabricate Cu/Co nanoparticles (NPs) embedded in nitrogen‐doped carbon matrices (Cu/Co@N‐C) through the carbonization of CuCo‐MOF precursors. Moreover, monometallic counterparts of Cu@N‐C and Co@N‐C were also prepared via carbonization of bimetallic CuZn‐MOF and CoZn‐MOF, respectively. Electrochemical tests confirm that Cu acts as the key active center for nitrite oxidation. By adjusting the Cu/Co molar ratios, a series of cubic Cu/Co@N‐C composites with tunable sizes of 200–500 nm were achieved. The synergistic interaction between metallic Cu/Co NPs and the conductive N‐C framework enhances catalytic activity and reduces overpotential compared to the monometallic Cu counterpart. The optimized Cu/Co@N‐C/glass carbon electrode (GCE) sensor delivered a superior sensitivity as high as 0.461 μA μM −1 cm −2 and wide detection range of 2–10000 μM. The Cu/Co@N‐C/GCE sensor also demonstrated superior selectivity, long‐term stability of 92.5% retention after 21 days, and reproducibility. This work establishes a versatile approach for engineering various MOF‐based catalysts, demonstrating promising potential for applications in environmental monitoring and food safety analysis.