Acid Protonation Promoted Different Crystal Phase Structure Silicon Carbide-Based Carbon Nitride Composite Enhances the Photocatalytic Degradation of Dye Wastewater

Abstract

The acid protonated silicon carbide supported carbon nitride photocatalytic composites with different crystal structures were successfully prepared by impregnation-heat treatment method (P-g-C3N4/β-SiC and P-g-C3N4/α-SiC). The samples were characterized by XRD, SEM, HRTEM, XPS, UV-vis-DRS and PL. The results showed that the acid protonated g-C3N4/β-SiC and g-C3N4/α-SiC materials were transformed from large-area lamellar structure to uniform and dispersed lamellar particles. The UV-vis-DRS and PL showed that the recombination probability of photogenerated electron-hole pairs of protonated g-C3N4/β-SiC and g-C3N4/α-SiC samples decreased and the band gap increased. The results of photocatalytic degradation of alizarin red S (ARS), acid fuchsin (AF) and basic fuchsin (BF) showed that the samples P-g-C3N4/β-SiC and P-g-C3N4/α-SiC had excellent photocatalytic degradation performance. It is worth noting that the degradation performance of the sample P-g-C3N4/β-SiC on the three dyes is better than that of P-g-C3N4/α-SiC. The ESR results showed that the ·O2- and ·OH produced by the two catalysts during the dye degradation process played a leading role in the degradation reaction. Fortunately, the catalyst maintains an excellent cycle life and can be reused more than seven times while degrading all three dyes.

Keywords: Photocatalysis, P-g-C3N4/β-SiC, P-g-C3N4/α-SiC, Degradation of dye wastewater