Sustainable and green synthesis of C- and N-doped nanoporous g-C3N4: powerful sunlight-responsive photocatalysts for aerobic oxidation of toluene

• Published in: Reaction chemistry & engineering 2023-07, Vol.8 (8), p.1914-1922
• Main Authors: Tavakolain, Mina, Jafari, Mitra, Ebrahimian, Mohammad Reza, Rahimpour, Mohammad Reza, Hosseini-Sarvari, Mona
• Format: Article
• Language: English
• Subjects: Carbon; Carbon nitride; Doping; Electron microscopy; Fourier transforms; Infrared analysis; Infrared spectroscopy; Microscopy; Nitrogen; Optical properties; Oxidation; Photocatalysis; Photocatalysts; Photoelectrons; Spectrum analysis; Sunlight; Synthesis; Thermogravimetric analysis; Toluene; X ray photoelectron spectroscopy
• ISSN: 2058-9883
• DOI: 10.1039/d2re00587e

Choosing green alternatives for chemical templates and doping agents is still challenging for scientists. In this study, for the first time, N- and C-doped graphitic carbon nitrides were synthesized via a green, sustainable, and facile strategy using a naturally abundant waste material, pomegranate peels. Based on the findings, the role of pomegranate peels was not only limited to bio-templates but they also played a selective role as a doping agent in a way that an increase in its loading led to a shift from nitrogen-doped to carbon-doped graphitic carbon nitride. Comparing with the pristine g-C3N4 revealed that the presence of a bio-template elegantly altered the physical and optical properties of the prepared materials. A comprehensive analysis including X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption–desorption, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy was employed to characterize the as-prepared materials. The photocatalytic potential of the synthesized graphitic carbon nitrides was investigated in the aerobic oxidation of toluene under sunlight irradiation. In this line, N-doped g-C3N4 with 0.05 wt% loading of bio-template, benefiting from the high surface area and efficient charge separation of photo-generated electron–hole pairs, was found to be the best photocatalyst, furnishing the desired product in 91% yield. Moreover, the metal-free photocatalyst could be recovered 6 times while maintaining its activity. These findings may open up a new way to synthesize metal-free photocatalysts to promote organic transformations in a more environmentally-friendly fashion.