Green exfoliation of graphitic carbon nitride towards decolourization of Congo-Red under solar irradiation

Reaction mechanism pathway for de-colorization of Congo-Red under solar irradiation. [Display omitted] •The g-C3N4 nano particles as visible light driven photocatalyst in bulk were synthesized by urea pyrolysis.•The bulk g-C3N4was exfoliated using the aqueous bi-thermal method.•The mechanism of aqueous bi-thermal method for exfoliation was discussed in detail.•The multi stage procedure yielded good quality exfoliated g-C3N4nano sheets.•It was observed that 1 g/L exfoliated g-C3N4 could decolorize up to 95.1% of a 100 ppm aqueousCongo Red solution under solar irradiation for 60 min. Exfoliated g-C3N4 nanoparticles were synthesized by the aqueous bi-thermal methods and were evalute during different analytical tools and techniques like XRD, PL, FTIR, UV–vis-DRS, FESEM, and HRTEM etc. The exfoliated g-C3N4 obtained using this green exfoliation technique provided material with improved band gap. The results of UV-VDRS spectrophotometer together with Mott-Schottky graphs of exfoliated g-C3N4 nanoparticles corroborated this observation. The sought after characteristics like effective separation and very low rate of recombination of photo-induced electron and holes and enhanced band-gap of exfoliated g-C3N4 are expected to increase the photocatalytic performance of semiconductor. The photo catalytic ability of the exfoliated g-C3N4were evaluated from solar decolourization studies of 100 ppm aqueous solution of Congo-Red (CR).The decolourization up to 95.1% could be achieved with 1 h exposure to sun light at catalyst concentration of 1 g/L. The experiments included scavenger tests for active species identification and prediction of CR decolourization mechanism. This project demonstrates a low cost, green method for exfoliation of g-C3N4 scalable further.