Enhanced visible-light degradation of organic dyes via porous g-C3N4

Abstract

Graphitic carbon nitride (g-C3N4) was prepared by reduction of melamine by adapting a pyrolysis method. Porous g-C3N4 (P-g-C3N4) was synthesized by altering the surface as well as the morphology of g-C3N4 by treating with oxidizing acids (chemical protonation). The photocatalytic activity of g-C3N4 and P-g-C3N4 are estimated by degrading various organic dyes namely methyl blue (MB), crystal violet (CV), and rhodamine B (Rh-B) irradiated under sunlight. The optical absorption edge of g-C3N4 was found to be blue-shifted from 2.7 eV to 3 eV on protonation. The g-C3N4 shows superior photocatalytic degradation efficiency in comparison with pristine g-C3N4. The P-g-C3N4 shows enhanced photocatalytic degradation efficiency of 98%, 99%, and 90% for MB, CV, and Rh-B, respectively, in 180 mins under sunlight irradiation with a rate of the reaction of about 4.046 min−1, 5.951 min−1, and 2.260 min−1. Reactive oxygen species experiments revealed that the production of. ·OH radicals are responsible for the deterioration of dyes. The boosted degradation efficacy of P-g-C3N4 is attributed to an increase in the surface area thereby exposing a large number of active sites for dye degradation.