A novel electrochemical sensor composed of a composite of Co ^II -MOF/acetylene black exhibits enhanced sensing behavior for glucose detection.

A good-performance glucose sensor based on Co ₃ O ₄ has been first synthesized by rationally designing a new cobalt–metal–organic framework precursor.

4-Nitrophenol (4-NP) is a typical organic pollutant, thus it is urgent to detect it in environmental samples. This study rationally designed a novel electrode material of P-doping Fe/Fe ₃ O ₄ @C (P-Fe/Fe ₃ O ₄ @C) prepared with MIL-88 as precursor. P _2h -Fe/Fe ₃ O ₄ @C-700 was synthesized by calcining MIL-88 at 700 °C, followed by annealing process with NaH ₂ PO ₂ for 2 h. The P _2h -Fe/Fe ₃ O ₄ @C-700 modified glassy carbon electrode (P _2h -Fe/Fe ₃ O ₄ @C-700/GCE) showed a high electrocatalytic activity toward 4-NP reduction due to its active metal center, fine-tuned electronic structure by P-doping, as well as good electrical conductivity. It exhibited excellent sensing behaviors in 4-NP detection with rather high sensitivities of 1415.43 μ A·mM ⁻¹ ·cm ⁻² and 424.63 μ A·mM ⁻¹ ·cm ⁻² in the 4-NP concentration of 5 to 100 μ M and 100 to 1200 μ M, respectively, with a low detection limit of 0.462 μ M. The P _2h -Fe/Fe ₃ O ₄ @C-700/GCE still had good selectivity for 4-NP detection in the presence of common interferences. In addition, it was found that the current response towards 4-NP at P _2h -Fe/Fe ₃ O ₄ @C-700/GCE retained more than 97% of its initial value after one week, indicating a good long-term stability. Furthermore, the P _2h -Fe/Fe ₃ O ₄ @C-700/GCE exhibited a good reproducibility. The constructed P _2h -Fe/Fe ₃ O ₄ @C-700/GCE achieved practical uses for the sensing of 4-NP in tap water with satisfactory recoveries.