Ultra-sensitive electrochemical sensor based on NiCoP bimetallic phosphide anchored on biomass-derived porous carbon for the detection of metronidazole residues

One-step green phosphidation using biomass guanine and phosphoric acid. • NiCoP anchored on N-doped carbon synergistically accelerates redox kinetics. • Optimized Ni/Co ratio induces lattice distortion for enhanced sensing. • High stability, selectivity, and accuracy in complex real-sample analysis. • Achieves ultra-sensitive MTZ detection (LOD: 0.029 μM, range: 0.05–350 μM). As a broad-spectrum antibiotic, metronidazole (MTZ) is extensively used in clinical and aquaculture fields. However, its continuous overuse leads to severe environmental accumulation, posing significant ecotoxicological risks and threatening human health. Herein, we developed an ultra-sensitive, eco-friendly electrochemical sensor for MTZ. The novelty of this work lies in utilizing natural biomass guanine as a dual carbon/nitrogen precursor and non-toxic phosphoric acid to in situ anchor bimetallic nickel-cobalt phosphide (NiCoP) onto nitrogen-doped porous carbon (NiCoP/GC) via a facile one-step process. Mechanistically, the synergistic effect among the highly conductive nitrogen-doped carbon skeleton, NiCoP bimetallic centers, and highly electronegative phosphorus significantly accelerates the proton-dependent electroreduction kinetics of MTZ. Providing specific quantitative advantages, the sensor achieves a broad linear range (0.05–350 μM) and an ultra-low detection limit of 0.029 μM. Crucially, it exhibits excellent anti-interference and reproducibility in complex real matrices, including honey, milk, and environmental water. In summary, the successful integration of biomass-derived carbon and bimetallic phosphide yields an ultra-sensitive sensor, providing a robust green platform for monitoring antibiotic residues in food and environmental ecosystems. Download: Download high-res image (165KB) Download: Download full-size image