Mesoporous silica-based carbon dot–carbon nitride composite for efficient photocatalysis

Abstract

In this work, graphene carbon nitride (g-C₃N₄, CN) is loaded into the carbon dots (CD) modified SBA-15 mesoporous silica by a precursor impregnation method. The obtained samples are characterized by various spectroscopy techniques and applied in the visible-light-driven photocatalytic degradation of phenol. The photocatalytic activity of the obtained SBA15–CN is 2 times as high as that of pure g-C₃N₄ due to the high dispersion of g-C₃N₄ into SBA-15 channels. For CD-SBA15–CN, the visible light driven photocatalytic activity is further increased, which is 4 times as high as that of pure g-C₃N₄. This promotion can be attributed to carbon dots with the ability to transfer photogenerated electrons as well as the compound catalyst having a bigger surface area and pore volume. When the weight ratio of CD-SBA15/g-C₃N₄ was 1 : 6, the catalyst (1 : 6 CD-SBA15–CN) performed best. The 1 : 6 CD-SBA15–CN photocatalyst had enhanced visible absorption and the interaction between CDs and g-C₃N₄ can further promote the separation of photo-generated electrons and holes, achieving the highest photocatalytic activity of CD-SBA15–CN compared to SBA15–CN and g-C₃N₄.