Maghemite nanoparticles decorated semiconducting graphitic carbon nitride hetero-structured nanocomposite: Facile synthesis, characterizations and its visible light active photocatalytic system for removal of hazardous organic pollutants from aqueous solutions

Hetero-structured nanocomposite consisting of graphitic carbon nitride host, decorated by γ-phase iron oxide, maghemite (γ-Fe₂O₃@G-CN) was synthesized in different mass contents of γ-Fe₂O₃ (5%, 10% and 20%) in the composite, by the method of nanosecond pulsed laser fragmentation, and defect engineering in liquid for the removal of hazardous organic pollutants from aqueous solutions. The elemental, structural, and morphological characterizations of the synthesized nanocomposites by XPS, XRD, TEM, and HR-TEM exhibited the proper anchoring of γ-Fe₂O₃ on the graphitic carbon nitride polymeric network. Also, the diffuse reflectance spectra, and the room temperature photoluminescence spectra respectively revealed that the presence of γ-Fe₂O₃ in graphitic carbon nitride brought about the enhanced and extended visible light absorption, and reduced recombination of photo induced electron hole pairs, the characteristics desired in a good photo-catalyst. Moreover, this composite material exhibited the z-scheme photo catalytic mechanism, where the more energetic electrons and holes in the composite band structure mediate the redox reaction in the photo-catalysis. The photo-catalytic efficiency of γ-Fe₂O₃@G-CN nanocomposite was evaluated in the photo-catalytic degradation of methyl blue (MB), and rhodamine-B (Rh-B) cationic dyes under visible light irradiations. For both the degradation processes, all the variants of γ-Fe₂O₃@G-CN nanocomposite consistently showed the enhanced photocatalytic efficiency with respect to pure GCN, with the maximum efficiency recorded for 10% γ-Fe₂O₃ in γ-Fe₂O₃@G-CN nanocomposite.