This study describes the preparation of graphitic carbon nitride (g-C₃N₄), hematite (α-Fe₂O₃), and their g-C₃N₄/α-Fe₂O₃ heterostructure for the photocatalytic removal of methyl orange (MO) under visible light illumination. The facile hydrothermal approach was utilized for the preparation of the nanomaterials. Powder X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX), and Brunauer–Emmett–Teller (BET) were carried out to study the physiochemical and optoelectronic properties of all the synthesized photocatalysts. Based on the X-ray photoelectron spectroscopy (XPS) and UV-visible diffuse reflectance (DRS) results, an energy level diagram vs. SHE was established. The acquired results indicated that the nanocomposite exhibited a type-II heterojunction and degraded the MO dye by 97%. The degradation ability of the nanocomposite was higher than that of pristine g-C₃N₄ (41%) and α-Fe₂O₃ (30%) photocatalysts under 300 min of light irradiation. The formation of a type-II heterostructure with desirable band alignment and band edge positions for efficient interfacial charge carrier separation along with a larger specific surface area was collectively responsible for the higher photocatalytic efficiency of the g-C₃N₄/α-Fe₂O₃ nanocomposite. The mechanism of the nanocomposite was also studied through results obtained from UV-vis and XPS analyses. A reactive species trapping experiment confirmed the involvement of the superoxide radical anion (O₂^•−) as the key reactive oxygen species for MO removal. The degradation kinetics were also monitored, and the reaction was observed to be pseudo-first order. Moreover, the sustainability of the photocatalyst was also investigated.

Photocatalysis and membrane technology in a single unit is an ideal strategy for the development of wastewater treatment systems. In this work, novel GO (x wt%)/TiO₂-CA hybrid membranes have been synthesized via a facile non-solvent induced phase inversion technique. The strategy aimed to address the following dilemmas: (1) Effective utilization of visible light and minimize e⁻/h⁺ recombination; (2) Enhanced separation capability and superior anti-fouling and self-cleaning ability. The experimental results reveal that the integration of nano-composite (GO/TiO₂) boosts the membrane properties when compared to pristine CA and single photocatalyst employed membrane (GO-CA and TiO₂-CA). The effect of GO content on the properties of the photocatalytic membrane has been determined by utilizing three different ratios of GO, viz. 0.5 wt%, 1 wt%, and 2 wt% designated as NC(1)-CA, NC(2)-CA, and NC(3)-CA, respectively. Amongst them, NC(3)-CA membrane showed state-of-the-art performance with an elevated photocatalytic response (four times higher than pristine CA membrane) toward methyl orange. Moreover, the water flux of NC(3)-CA membrane is 613 L/m²h, approximately three times higher than bare CA membrane (297 L/m²h), while keeping the MO rejection high (96.6%). Besides, fouling experiments presented the lowest total and fouling resistance ratios and a higher flux recovery ratio (91.78%) for the NC(3)-CA membrane, which endows the membrane with higher anti-fouling and self-cleaning properties. Thus, NC(3)-CA membrane outperforms the other as synthesized membranes in terms of separation efficiency, visible light photo-degradation of pollutant, anti-fouling and self-cleaning ability. Therefore, NC(3)-CA membrane is considered as the next generation membrane for exhibiting great potential for the wastewater treatment applications.

A facile and room temperature approach to synthesize pure TiO₂ and different variants of nirogen and cobalt co-doped TiO₂ (CoN-TiO₂) catalysts is reported in this study. The successful synthesis and crystalline phase analysis was carried out via X-ray diffraction (XRD) which confirmed anatase phase with tetragonal structure. The spherical morphology, uniform size distribution in the range of 20-40 nm and presence of dopants in final product were validated by scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDS). Diffused reflectance spectroscopy (DRS) is deployed for study of optical properties. A reduction in band gap from 3.2 eV for pure TiO₂ nanoparticles to 2.34 eV for the 7 wt.%. doped CoN-TiO₂ was observed. The photocatlytic activity of pure TiO₂, and CoN-TiO₂ nanoparticles was studied against methyl orange.The photocatlytic activity of CoN-TiO₂ was almost double as compared to undoped TiO₂ which proves these catalysts to be very efficient and potential candidate for the wastewater treatment at industrial level.