Novel fumed silica/g-C3N4 composites for highly efficient removal of rhodamine B under visible light emitting diodes light irradiation

Graphitic carbon nitride (g-C 3 N 4 ) is a fascinating nonmetallic photocatalyst for the removal of environmental pollutants. The fumed silica/g-C 3 N 4 (gCN-FS) composite photocatalysts were successfully fabricated by a combination of solvent volatilization and post-annealing methods. The introduction of SiO 2 not only widens the absorption range of visible light, but also enhances the specific surface area of g-C 3 N 4 . The gCN-FS-3 composite has a BET surface area of 129.89 m 2 /g, which is ~3.3 times as much as that of g-C 3 N 4 (39.54 m 2 /g). The gCN-FS composites have markedly improved rhodamine B (RhB) photodegradation activity in comparison to pure g-C 3 N 4 , bulk g-C 3 N 4 and P25 under 557 nm yellow-green light emitting diode light irradiation. The gCN-FS-3 has the highest RhB photodegradation rate, which is ~9.67-, 11.81-folds as compared to bare g-C 3 N 4 and bulk g-C 3 N 4 , respectively. The coupling effect between the increase in specific surface areas and the inhibition effect of SiO 2 on photogenerated electron/hole pairs recombination is responsible for the enhanced visible light photocatalytic activity of gCN-FS composite. Superoxide and holes are responsible for the RhB photocatalytic degradation. Furthermore, no apparent loss of photocatalytic activity over five cycles is observed, which indicates that the gCN-FS composites have considerable stability and reusability in the photodegradation process. The gCN-FS composites show great promise in visible light driven photocatalysis for environmental applications.