Cobalt modified mesoporous graphitic carbon nitride with enhanced visible-light photocatalytic activity

Abstract

Mesoporous graphitic carbon nitride (mpg-C₃N₄) was synthesized using silica nanoparticles as the hard template, and cobalt modified mpg-C₃N₄ (Co₃O₄/mpg-C₃N₄) was prepared via a facile impregnation method. UV-vis spectra showed that the mpg-C₃N₄ exhibited obvious absorption in the visible light range. The XPS results proved that the cobalt species deposited on mpg-C₃N₄ samples was Co₃O₄. The photocatalytic activity of Co₃O₄/mpg-C₃N₄ was evaluated in the photocatalytic degradation of bisphenol A (BPA) in aqueous solutions under visible light irradiation (λ > 420 nm). The photocatalytic degradation efficiency of BPA by Co₃O₄/mpg-C₃N₄ was significantly higher than that of mpg-C₃N₄ and the optimum content of Co₃O₄ loaded in the mpg-C₃N₄ was 1.5 wt%. Radical-trapping experiments certified that both hydroxyl radicals and superoxide radicals were the active species for the photocatalytic degradation of BPA. The total organic carbon (TOC) removal showed that BPA was mineralized by 1.5% Co₃O₄/mpg-C₃N₄ under visible light irradiation. The recycling tests indicated that 1.5% Co₃O₄/mpg-C₃N₄ was quite stable and there was no obvious decrease in photocatalytic activity after 5 cycles.