ZnFe₂O₄/Fe-embedded honeycomb 3D macroporous N-doped carbon for high-performance detection of sunset yellow

The design and preparation of electrochemical sensors capable of sensitively detecting the food additive sunset yellow (SY) are essential for food safety analysis. This work obtained ZnFe₂O₄/Fe highly dispersed in three-dimensional (3D) honeycomb nitrogen-doped carbon by high-temperature pyrolysis of bimetallic doped polymers. Uniform and tiny ZnFe₂O₄/Fe nanoparticles were dispersed on the surface of nitrogen-doped carbon nanosheets, with the active sites fully exposed. The continuous pore structure provides several mass transfer pathways. The multivalent transition metal ions have a strong adsorption capacity for SY molecules. Density functional theory (DFT) calculations demonstrate that the SY molecule exhibits the strongest adsorption energy on the FeZn@NC-700 surface compared to ZnO@NC-700 and FeC@NC-700. The linear range of the constructed FeZn@NC-700/GCE sensor for detecting SY was 1 × 10^-8 M - 1 × 10^-6 M, and the lowest limit of detection (LOD) was 4.7 × 10^-9 M. This study provides a new idea for designing polymer-derived carbon materials.