Nitrogen doped carbon quantum dots@α-Fe2O3/PANI nanocomposite based electrochemical sensor for cadmium ion detection

Cadmium (Cd2+) ions pose significant risks due to their toxic effects even at low concentrations. By integrating nitrogen-doped carbon quantum dots (N-CQDs) with alpha-Fe2O3 and polyaniline (PANI), we have engineered a nanocomposite that demonstrates a remarkably high sensitivity and selectivity in detecting Cd2+ ions. The NCQDs@alpha-Fe2O3/PANI nanocomposite was prepared by using hydrothermal and in-situ polymerization methods. The characterization techniques for an eco-friendly polymer nanocomposite confirm the interactions between N-CQDs, alpha-Fe2O3, and PANI. X-ray diffraction analysis shows the nanocomposite possesses a crystal size of 24 +/- 0.03 nm. Field-emission scanning electron microscope and high-resolution transmission electron microscope images showed that the spherical N-CQDs are enclosed by irregular alpha-Fe2O3 nanoparticles, which are dispersed on the PANI sheets. Further, the particle size distribution analysis indicates an average size of 5.8 nm for the N-CQDs. The electrochemical sensing result suggests that the nanocomposite is effective in sensing the Cd2+ ions with a detection limit of 750 nm.