Identifying Superior Binding Sites for Lead Detection on Solvothermally Engineered Fluorescent Active Heteroatom-Doped Carbon Nanofibers

Aiming to decipher the role of optimum binding site for detection of lead ions, fluorescent active heteroatom-doped carbon nanofibers-based materials (O-CNF, N-CNF, sulfur-containing material (S-CNF), and NS-CNF) are fabricated solvothermally. The S-CNF exhibits highest detection efficiency for fluorescent sensing of lead ions as compared to other materials. The S-CNF detects lead ions with 5.99 μM detection limit in a concentration range of 0–40 μM. FESEM and HRTEM analysis of S-CNF reveals the hybrid morphology, where spherical units formed from elemental sulfur are aggregated on the surface of carbon nanofibers. X-ray diffraction pattern reveals amorphous nature of the material, and incorporation of sulfur atom is confirmed through X-ray photoelectron spectroscopy. Various functional groups such as >CO, ROR, COOH, SO, SS, CSC, and CS are found to be present in S-CNF. The binding sites for the lead ions are confirmed by adsorbing the metal ions on S-CNF surface that are clearly seen on FESEM–EDS analysis. The final proof for the involvement of SO and other sulfur-bearing functional groups (SS, CSC, and CS) is performed by Fourier-transform infrared spectroscopy. The investigation clarifies role of various oxygen-, nitrogen-, and sulfur-containing functional groups for the efficient removal of toxic lead metal in contaminated water samples.