Highly efficient and stable Fe2O3/g-C3N4/GO nanocomposite with Z-scheme electron transfer pathway: Role of photocatalytic activity and adsorption isotherm of organic pollutants in wastewater

In this work, we have used a hematite ferric oxide (Fe2O3), graphitic carbon nitride (g-C3N4), and graphene oxide (GO) to design highly efficient visible light active ternary nanocomposite for the exclusion of organic contaminants in an aqueous system. The reusability test and powder X-ray diffraction (XRD) analysis of 10 wt% Fe2O3/g-C3N4/GO (10FGG) nanocomposite before and after four consecutive cycles run demonstrated that the synthesized photocatalyst has impressive stability. The X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray (EDX) analyses indicate the presence of all the elements in the composite material without any impurities. Among the synthesized materials, the photocatalytic degradation of rhodamine B (RhB), methylene blue (MB) and 3-methyl-4-nitrophenol were best achieved by 10FGG nanocomposite. High-performance liquid chromatography (HPLC) analysis showed the transformation of 3-methyl-4-nitrophenol into 3-methyl-4-aminophenol as one of the intermediate products followed by complete degradation under visible light irradiation. The terephthalic acid photoluminescence (TA-PL) experiment in NaOH and nitroblue tetrazolium (NBT) in water reveal the continuous generation of hydroxyl and superoxide radicals, respectively. The low PL signal for 10FGG revealed that Fe2O3, g-C3N4, and GO could collectively minimize the recombination rate of electron-hole pairs and hence raise the sum of carrier charges (h+ and e−) accessible for photoreactions, confirming the improved photocatalytic activity of nanocomposite. Based on the data obtained, a plausible Z-scheme photodegradation mechanism of the pollutants with 10FGG nanocomposite has been sketched out.