Synthesis of g-C3N4/Ba-ZnO Nanocomposites for Photocatalytic Degradation of Methylene Blue and Antibacterial Application

Abstract

Photocatalytic degradation is an effective method to reduce environmental pollution caused by organic pollutants. In this work, the photocatalytic and antibacterial activity of graphitic carbon nitride (g-C3N4) coupled with Barium doped zinc oxide (Ba-ZnO) composite material was studied. The polymeric g-C3N4 materials were fabricated by the pyrolysis of urea. ZnO and Ba-ZnO nanoparticles were produced by a coprecipitation method. More importantly, g-C3N4/Ba-ZnO nanostructured composites were fabricated by adding the different amounts of graphitic carbon nitride (10%, 20% 30%, 40%, 50%, 60%) into Ba-doped ZnO via the simple co-precipitation method. The fabricated materials were characterized by X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy (UV-vis-DRS), Fourier transform infrared (FT-IR) spectroscopy, and scanning electron microscopy (SEM). XRD results have revealed that the ternary NC exhibited new peaks which evidenced the successful incorporation of Ba and g-C3N4. The incorporation of Ba and g-C3N4 into the ZnO matrix has shifted the absorption edge toward the visible region as observed in UV-DRS spectra. FTIR spectra manifested the presence of the characteristic absorption peak at 571 cm−1 of Zn–O bending vibrational modes confirming the target nanoparticles synthesis. The SEM images revealed random-shaped rough morphology for the NC with a clear influence of the presence of Ba and g-C3N4. All the fabricated nanomaterials were investigated for their photocatalytic activity by using methylene blue (MB) dye. Ternary NCs, in which 50% g-C3N4 hybridized with Ba-doped ZnO (g-C3N4/Ba-ZnO) NCs were proven to be optimum photocatalysts for the degradation of methylene blue (MB) dye under sunlight irradiation. Further, parameters such as the effect of pH of the dye solution, catalyst loading, and initial dye concentration were also studied and optimum degradation efficiencies were found at pH 9, 0.3 g catalyst loading, and 10 mg/L dye concentration. Moreover, the reusability of the recovered photocatalyst was studied efficiently up to 5 cycles in the degradation process. The synthesized photocatalysts were also applied against Gram-positive (S. aureus and S. pyogen) and Gram-negative (E. coli and P. aeruginosa) bacterial strains to evaluate their antibacterial activities. The antibacterial activity of the 50% g-C3N4/Ba-ZnO NC was compared to other synthesized nanomaterials and found to have better inhibition zone values against all studied bacterial strains.