Catalytic activity of porous carbon nitride regulated by polyoxometalates under visible light

A series of porous carbon nitrides modified by different polyoxometalates (POMs) were prepared by the ultrasonic method. POMs were assembled on the surface of mpg-C₃N₄ via electrostatic attraction. The catalyst has visible light degradation activity for phenol (λ > 420 nm). mpg-C₃N₄ modified by H₄SiW₁₂O₄₀ with a mass ratio of 1 : 5 showed the highest catalytic activity, which was 3.5 times higher than that of mpg-C₃N₄. As an electron acceptor, polyoxometalate can capture the photoelectron of C₃N₄, which can promote the separation of photocharge and improve the photocatalytic activity. ESR also confirmed that the superoxide radicals play a major role in degradation. The results show that the charge separation efficiency and catalytic activity can be enhanced by polyacids.