A comparative photocatalytic study of pure and acid-etched template free graphitic C3N4 on different dyes: An investigation on the influence of surface modifications

In this study, the photocatalytic properties of graphitic carbon nitride (g-C3N4) and strategically developed acid-etched template free graphitic carbon nitride (Tg-C3N4) photocatalyst on cationic viz. Methylene blue (MB), Rhodamine B (RhB) and anionic viz. Methyl orange (MO) and Congo red (CR) dyes have been compared for the first time. g-C3N4 was prepared from melamine at 550 degrees C using thermal condensation method and Tg-C3N4 by acid-etched template free method through exfoliation of bulk g-C3N4 using ternary mixture of H2SO4-HNO3 (1:1) ratio with H2O2. The photocatalysts were characterized by XRD, FTIR, RAMAN, TRPL, FESEM, BET, Zeta potential, UV-Vis and XPS. The specific surface area was found to be improved from 11.12 m(2)/g to 17.05 m(2)/g and zeta value shifted from 0.53 mV to 6.74 mV in Tg-C3N4 as compared to g-C3N4. The enhanced photodegradation efficiency and fast reaction kinetics of Tg-C3N4 as compared to g-C3N4 was attributed to large specific surface area, high positive zeta potential, reduced bandgap and lower electron-hole recombination rate. The effect of different pH, scavengers, reusability, durability and stability of Tg-C3N4 was also checked.