Incorporation of CoO nanoparticles in 3D marigold flower-like hierarchical architecture MnCo2O4 for highly boosting solar light photo-oxidation and reduction ability

Abstract

Most previous reported photocatalysts designs show that, either photocatalytic oxidation (PCO) or reduction (PCR) is inhibited due to the insufficient govern of the photo-excited h+ and e−. To overcome this problem, we consider that both PCO and PCR could be improved simultaneously by employing suitable photocatalyst. Herein, the novel 3D marigold flower-like hierarchical architecture CoO@MnCo2O4 was successfully synthesized by anchoring CoO nanoparticles (NPs) on MnCo2O4 flower using a facile solvothermal method followed thermal annealing treatment under N2 atmosphere for the first time. This strategy relies on the formation of a p-n heterostructure with matching energy band gaps, in which CoO NPs tightly adhere to the surface of hierarchical MnCo2O4 microflowers, and the flower-like MnCo2O4 act as scaffold to disperse CoO NPs. The as-fabricated CoO@MnCo2O4 hybrid not only presented remarkable performance for PCO of tetracycline (TC) but also exhibited excellent PCR of hexavalent chromium (Cr (VI)) under visible light irradiation. Meanwhile, the photocatalyst also can be used for treatment a mixture of them and exhibited promoted photocatalytic efficiency. That's the primary reason that h+ and e- can play their own roles to accomplish PCO and PCR, respectively. Moreover, the unique 3D hierarchical microflowers structure not only provide a higher specific surface area, sufficient active sites and enhanced light harvesting, but also significantly decrease the aggregation of CoO particles. The appearance photocatalytic mechanism of the p-n heterostructure system was also discussed in detail. The facile synthesis strategy and outstanding photocatalytic performance make the 3D hierarchical architecture CoO@MnCo2O4 a promising candidate as a visible light photocatalyst.