Fabrication and characterization of g-C3N4/PANI/ZnO ternary nanocomposites: Structural, optical, and antibacterial investigations

A novel Graphitic Carbon Nitride-Polyaniline-Zinc Oxide ternary Nanocomposites (g-C 3 N 4 /PANI/ZnO NCs) is successfully synthesized through a three-step process involving calcination, in situ polymerization, and coprecipitation. The nanocomposites with varying concentrations of g-C 3 N 4 and PANI (1, 3, 5, and 10 wt%) are synthesized. The synthesized NCs are characterized using X-ray Diffraction (XRD), Photoluminescence Spectroscopy (PL), UV-Visible Diffuse Reflectance Spectroscopy (UV-DRS), Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FESEM), and Energy Dispersive X-ray Spectroscopy (EDX). XRD analysis confirmed that the synthesized NCs are polycrystalline, with a hexagonal wurtzite structure, and that crystallite sizes ranged from 18.9 to 29.2 nm. TEM analysis showed particle sizes in the range of 23.2–33.3 nm. An optical band gap of 3.30 eV is obtained for pristine ZnO from UV-DRS analysis, which progressively declined from 3.19 to 2.89 eV for the g-C 3 N 4 /PANI/ZnO NCs with increasing g-C 3 N 4 and PANI content. FESEM confirmed the uniform dispersion of ZnO on the g-C 3 N 4 /PANI matrix. FTIR and PL analyses further verified the chemical interaction and interfacial integration between g-C 3 N 4 /PANI and ZnO. Detailed characterization confirmed the uniform dispersion and successful integration of ZnO on the g-C 3 N 4 /PANI matrix. The antibacterial activity of the synthesized NCs is evaluated using agar well diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) assays, against both Gram-positive ( Staphylococcus aureus) and Gram-negative ( Escherichia coli , Pseudomonas aeruginosa , and Klebsiella sp.) bacteria. Among the tested samples, the 10 wt% g-C 3 N 4 /PANI/ZnO nanocomposite exhibited the largest inhibition zone (29 mm) against Pseudomonas aeruginosa , demonstrating its potential for antimicrobial applications.