Highly Efficient Solar‐Catalytic Degradation of Reactive Black 5 Dye Using Mesoporous Plasmonic Ag/g‐C <sub>3</sub> N <sub>4</sub> Nanocomposites
Fatemeh Asadi, Elaheh K. Goharshadi, Mohammad Sadeghinia
Abstract
Abstract An azo dye, Reactive Black 5 (RB5), was degraded by three photocatalysts of g‐C 3 N 4 , Ag(2 %)/g‐C 3 N 4 , and Ag(5 %)/g‐C 3 N 4 with the specific surface areas of 34.41, 28.70, and 35.58 m 2 g −1 and the band gaps of 2.52, 1.56, and 1.71 eV under sunlight illumination, respectively. The results showed 40 mg/L of g‐C 3 N 4 could degrade completely 10 ppm RB5 at pH 3.4 within 10 min under sunlight irradiation with the first‐order rate constant of 0.312 min −1 . Under the same conditions, the complete degradation time of RB5 reduced to 5 and 7 min when the plasmonic nanocomposites of Ag (2 %)/g‐C 3 N 4 and Ag (5 %)/g‐C 3 N 4 were used as photocatalysts, respectively. Ag content had an important influence on the photocatalytic activity of g‐C 3 N 4 against RB5 so that Ag (2 %)/g‐C 3 N 4 possessed the best photocatalytic efficiency with the rate constant of 0.795 min −1 . In fact, Ag nanoparticles through the surface plasmon resonance effects and by accepting the photogenerated electrons could improve the visible‐light absorption and increase charge separation of g‐C 3 N 4 . The results showed superoxide radical is the main oxidant in the photodegradation of RB5.