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

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 .