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 contam-inants 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 syn-thesized 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-amino -phenol 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.

Automated summary

The synthesized nanocomposite showed high efficiency in removing organic contaminants in water systems, with good stability and photocatalytic activity. It can reduce the recombination rate of electron-hole pairs, increasing the total carrier charge for improved photocatalytic activity.