Photocatalyst Co3O4/red phosphorus for efficient degradation of malachite green under visible light irradiation

Abstract Co3O4/red phosphorus (Co3O4/RP) photocatalysts were synthesized via facile hydrothermal and mechanically grinding approach. The catalysts were characterized via XRD, TEM, XPS, N2 sorption, photoelectro chemical measurements and UV–vis DRS. The results showed that the Co3O4 nanocrystals were assembled on the surface of the RP. The loading of Co3O4 on RP was beneficial to enhance the light absorption compared with pure RP. Under visible light, 94.5% of malachite green (MG) can be photodegraded within 20 min over 10% Co3O4/RP composite, while only 17.3% and 59.9% of MG can be photodegraded over pure Co3O4 and RP. The reaction rate constant k obtained over 10% Co3O4/RP heterojunction (0.1464 min−1) is approximately 3.2 times that of pure RP (0.0457 min−1), and 15.3 times that of bare Co3O4 (0.0096 min−1). The cycle experiments showed that the catalyst had high photocatalytic stability. Co3O4 nanocrystals inhibit the photoelectron-hole pair recombination of red phosphorus semiconductor, and exhibit improved visible light absorption. Consequently, the catalytic performance of Co3O4/RP has been enhanced under visible light.