Synthesis of porous g-C3N4 nanosheets with carbon vacancies for photodegradation of direct red 227 and direct black 166 dyes in aqueous solutions

Abstract

Porous graphitic carbon nitride (g-C3N4) nanosheets with carbon vacancies were synthesized by recalcination of bulk g-C3N4 in a muffle furnace in static air for 2 h at 550 °C. The synthesized product (RCN) was characterized using XRD, FESEM, FTIR, DRS, PL, EDX, and BET-EJH. The photoactivity efficiency of RCN was evaluated by its ability to degrade two heavy anionic textile dyes, direct Red 227 and direct Black 166, under visible light. The results showed RCN in the presence of OH− anions can degrade the mentioned dyes under visible light in a relatively short time. The free radical trapping tests showed that ·O2− is the active species and mainly responsible for color degradation, while the OH− ions from KOH (as a co-catalyst) increased the degradation rate by trapping the photogenerated holes (h+). Combination of photocatalyst and OH− as co-catalyst was used for the first time to degrade anionic textile dyes, direct Red 227 and direct Black 166.