Self-supporting Co-MOF@CP electrochemical sensor via one-step electrodeposition for sensitive nitrite sensing

In-situ growth of Co-MOF on carbon paper via one-step electrodeposition. • Co-MOF@CP electrochemical sensor was developed for sensitive detection of nitrite. • The sensor exhibits a wide linear range of 1–10,000 μmol/L, with LOD of 0.091 μmol/L for nitrite. • The sensor shows excellent selectivity, stability, repeatability, and reproducibility. • High sensitivity in the detection of nitrite in real samples. Reliable quantification of nitrite (NO 2 − ) is of great practical significance for food-safety supervision. In this work, a binder-free self-standing Co-MOF@CP electrode was prepared through a one-step electrodeposition route for high-performance nitrite determination in practical samples. Three-dimensional carbon paper (CP) acts as a porous conductive scaffold, supplying abundant nucleation sites while facilitating analyte accumulation. Meanwhile, Co-MOF delivers large specific surface area and plentiful catalytically active centers. Benefiting from their interfacial synergistic effect, charge-transport behavior and electrocatalytic reaction kinetics are greatly promoted, which further improves catalytic performance and long-term operational stability. Multiple characterizations including SEM, XRD, XPS, EIS and cyclic voltammetry (CV) demonstrate that CoMOF@CP possesses much larger electrochemically active surface area as well as lower charge-transfer resistance compared with Co(OH) 2 @CP and bare carbon paper. The constructed sensor achieves a low limit of detection of 0.091 μmol/L, accompanied by favourable anti-interference capacity, acceptable repeatability, fabrication reproducibility and operational stability. Real-sample recovery measurements yield spike recovery values ranging from 98.50% to 101.50%, with all RSD values less than 5.0%. This study not only establishes a dependable sensing platform for nitrite analysis but also offers a generalizable fabrication route for electrochemical sensors targeting trace contaminant detection. Download: Download high-res image (156KB) Download: Download full-size image