Specific temperature-modulated crab shell-derived porous carbon as a typical recycling material for nitrofurazone electrochemical sensor

Nitrofurazone (NFZ), a nitroimidazole antibiotic, can cause serious toxicity when overused, its quantification is crucial for human health. Herein, crab shell waste is converted into porous biochar at a high temperature, which can be employed for the establishment of an electrochemical sensor for the quantitative detection of NFZ. The morphological and structural properties of the crab shell carbon at different temperatures were characterized by SEM, XRD, FT-IR and N₂ adsorption-desorption analyses. The crab shell carbon prepared at 500 °C (C-CS-500) and 700 °C (C-CS-700) is calcite-based and contains micro-fibrillar similar to chitin structure, while the crab shell carbon prepared at 900 °C (C-CS-900) is lime-based and lacks the similar structure. And the synergistic influence of calcite-based composition and micro-fibrillar structure of crab shell carbon offered strong electron-transport properties and a large electrode active at a higher carbonized temperature. The electrochemical signals demonstrated that the crab shell carbon prepared at 700 °C provided enhanced sensing capability for rapid NFZ detection with a wide linear range of 0.40–80 μM, a high sensitivity of 0.55 μA μM⁻¹ and a low detection limit of 0.11 μM (S/N = 3), as compared to the crab shell carbon prepared at 500 °C and 900 °C. In addition, the sensor can also be utilized to quantify nitrofurazone in the real drug (compound cod liver oil ointment) with satisfactory recovery.