Cobalt–nitrogen–carbon nanocomposite as a high-surface electrocatalyst for ultrasensitive electrochemical detection of nitroaromatic pollutants

A cobalt–nitrogen–carbon (Co–N–C) nanocomposite was synthesised via one-step pyrolysis using cobalt nitrate, melamine, and Ketjen black for the electrochemical detection of 4-nitrotoluene (4-NT). Structural and morphological characterisation confirmed well-dispersed cobalt active sites within a porous nitrogen-doped carbon framework, exhibiting a surface area of 102.6 m2 g-1. The Co–N–C-modified glassy carbon electrode demonstrated enhanced electron-transfer kinetics and an electrochemically active surface area of 1.93 cm2. It exhibited excellent electrocatalytic activity towards 4-NT reduction, achieving a sensitivity of 0.55 µA µM-1 and a detection limit of 82 nM, along with good operational stability. The enhanced sensing performance is attributed to the synergistic effects of cobalt active sites and nitrogen-doped carbon, promoting electron transfer and analyte interaction. These results demonstrate the potential of Co–N–C as a low-cost electrocatalyst for nitroaromatic compound detection, warranting further validation of selectivity, reproducibility, and long-term stability.