Mesoporous V2O5/g-C3N4 Nanocomposites for Promoted Mercury (II) Ions Reduction Under Visible Light

The present study addresses a successful attempt to promote the photocatalytic reduction of mercury ions (Hg2+) over the synthesized V2O5/g-C3N4 by MCM-41 and F-127 templates under the visible light. V2O5 nanoparticles (NPs) were incorporated to g-C3N4 with the percentages of 0.3, 0.6, 0.9 and 1.2 wt%. The synthesized heterojunctions were verified to have large surface areas of 188–206 m2 g−1. It has been shown by TEM analysis that the constructed nanocomposites consist of uniformly dispersed V2O5 NPs over the g-C3N4 surface. The estimated bandgap energy is reduced from 2.7 eV for the pure g-C3N4 to 2.31 eV for the 1.2% V2O5/g-C3N4. The reduction of Hg2+ ions over the nanocomposite containing 0.9 wt% V2O5 under visible light was accomplished with the greater rate (480.23 µmol g−1 h−1), especially when compared to those over pure V2O5 NPs (110.00 µmol g−1 h−1) or pure g-C3N4 (85.22 µmol g−1 h−1). The optimized heterojunction achieved the entire reduction of Hg2+ after illumination by visible light whereas, only 23 and 16% of Hg2+ were reduced when pure V2O5 NPs and pure g-C3N4, respectively, were applied. The promoted achievement of the progressed heterojunction is ascribed to numerous factors like boosted surface area, confined bandgap, uniform dispersion of V2O5, and photocharge recombination suppression. The outstanding photocatalytic applicability of the V2O5/g-C3N4 heterojunctions was reached after reusing five times to reduce Hg2+ under visible light, implying the appreciable stability. This work highlights the practical use of modified g-C3N4-based photocatalysts for green remediation of water systems.