Biphasic g-C3N4-AgI nanocomposites and their applications in methylene orange degradation, the hydrogen evolution reaction and antimicrobial activity

In this study, pure g-C 3 N 4 , AgI, and biphasic g-C 3 N 4 -AgI nanomaterials were synthesized for photocatalytic and antimicrobial applications. Polyvinyl alcohol (PVA) was used to reduce surface agglomeration in the biphasic g-C 3 N 4 -AgI nanomaterial. The synthesized materials were characterized by XRD, BET, SEM, HR-TEM, EDS, SAED, DRS, PL, and EIS to study surface phase, surface area, surface morphologies, elemental composition, optical properties, and electron-hole pairs separation efficiencies. The XRD pattern of the AgI and g-C 3 N 4 appeared in the g-C 3 N 4 -AgI nanocomposite, which confirms the successful integration of AgI into the g-C 3 N 4 matrix. The calculated band gap energy of the g-C 3 N 4 , AgI and g-C 3 N 4 -AgI nanomaterials was 2.75 eV, 2.63 eV and 2.35 eV. The reduced bandgap of the biphasic is due to the synergetic effects of the single materials. The BET results showed a significant increase in surface area for the g-C 3 N 4 -AgI (98 m 2 /g) compared to AgI (20 m 2 /g) and g-C 3 N 4 (32 m 2 /g). This surface area modification in turn enhanced the catalytic potential of the g-C 3 N 4 -AgI composite. The antibacterial and photocatalytic potentials of all the as-synthesized materials were examined. The maximum photodegradation (94.5%) and hydrogen production (623 μmol/g) rates were observed for the g-C 3 N 4 -AgI composite. Higher inhibition zones of 20.6 ± 0.34 and 21.8 ± 0.36 mm were observed at 100 μg/mL of g-C 3 N 4 -AgI against Staphylococcus aureus and Escherichia coli , respectively, as compared to other synthesized materials. These results indicate that g-C 3 N 4 -AgI nanocomposite exhibited the highest levels of dye degradation, hydrogen production, and bacteriostatic action.