Exploring the photocatalytic degradation of methylene blue and carbol fuchsin dyes by magnesium codoped on graphene oxide and titanium dioxide green composites

Abstract

This research synthesized and characterized nature friendly green composites comprising graphene, titanium, and magnesium oxides (GO–TiO₂/MgO) and its dye degradation efficiency. The deposition of GO–TiO₂/MgO nanocomposites were achieved using ultrasonication, followed by the synthesis of green composites using Moringa oleifera seed extract as reductant. Crystallographic studies were confirmed by X-ray diffraction, functional groups and presence of elements were confirmed using Fourier-transform infrared spectroscopy (FTIR) and energy dispersive X-ray analysis (EDAX). Phase structure and vibrational modes were authenticated using Raman spectroscopy. Photoluminescence studies conveys the electrical characterization. Morphology of the samples were verified using Field emission scanning electron microscopy (FESEM) and High-resolution transmission electron microscopy (HRTEM). Among the samples, NC MgO1 displays PSD (Particle size distribution) of 8.8 nm with bandgap energy of 3.26 eV with crystalline size 21 nm possessing surface area of 70 m²/g exhibits better photocatalytic activity. N₂ Adsorption–Desorption analysis reveals the pore radius, volume, and surface area of the specimen. Selected area electron diffraction (SAED) pattern exhibits the sample’s polycrystalline nature, with diffraction signals matches with the MgO and TiO₂ anatase crystalline phase, while FESEM analysis corroborated the morphological modification of TiO₂ after GO incorporation and sensitization. Optical analyses indicated enhanced properties of TiO₂ in the visible range with the presence of natural sensitizer (Moringa oleifera seed extract) MgO and GO. Additionally, photocatalytic degradation studies of methylene blue and carbol fuchsin under UV visible irradiation in aqueous solution, employing a pseudo-first-order model, revealed a significant synergistic effect of 85% yield at 90 min with a rate constant and correlation efficiency for methylene blue was 0.018764/min and 0.98453 and for carbol fuchsin it was found to be 0.0227538/min and 0.9956.