LAUSR

There is an urgent need to construct highly selective low-cost sensors for fast detection of toxic metal ions such as cadmium. When compared with 3D bulk materials, 2D layered materials after activation treatments show superior performances for electrochemical metal ion detection. The bulk graphitic carbon nitride (hereafter b-g-C3N4) was prepared by thermal polymerization with urea as a precursor; it was then activated through ultrasonic liquid exfoliation and protonation which resulted in successful fabrication of activated ultrathin g-C3N4 nanosheets (hereafter a-g-C3N4). The a-g-C3N4-modified glassy carbon electrode demonstrates excellent electrochemical performances for Cd2+ detection with 22.668 μA/μM sensitivity and 3.9 nM LOD (S/N = 3) due to high specific surface area and active sites created on the 2D layered structure. The chemical interference of Pb2+, Cu2+, and Hg2+ on Cd2+ detection was minimal. We have also measured Cd2+ in natural water and rice samples using the newly developed a-g-C3N4-modified electrode with high spike recoveries. Our results demonstrate the potential applications of newly developed a-g-C3N4-modified electrode for rapid detection of toxic metal ions in different sample matrixes. Graphical Abstract The activated g-C3N4 nanosheets (a-g-C3N4) were synthesized and used to construct electrochemical sensors with high sensitivity and anti-interference performance. The activated g-C3N4 nanosheets (a-g-C3N4) were synthesized and used to construct electrochemical sensors with high sensitivity and anti-interference performance.