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

Abstract 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 °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 m2/g to 17.05 m2/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 band gap and lower electron-hole recombination rate. The effect of different pH, scavengers, reusability, durability and stability of Tg-C3N4 was also checked.