Preparation of “green” carbon quantum dots coated core-shell type pearl pigment Kieselguhr@TiO2@TiO2-x

In this paper, the green and environmentally friendly pearlescent pigment particles of the core-shell type kieselguhr@TiO2@TiO2-x composite were prepared via sol-gel deposition method, the surface of kieselguhr coated by TiO2, and then the surface of the composites was coated with TiO2-x by the technique of co-precipitation and the route of pyrolysis of the hydrazine salt. Orthogonal design method was employed to study the effects of different operating parameters on properties of the core-shell type kieselguhr@TiO2@TiO2-x composite. Due to characteristics of large specific surface with a lot of hydroxyl groups, the composite pigment were coated with Carbon dots with the assistance of (3-aminopropyl)trimethoxysilane (APS). Thus, the prepared composite pigment was mixed with citric acid and APS followed by hydrothermal reaction at 180 °C to generate carbon quantum dots coated composite pigment (kieselguhr@TiO2@TiO2-x@CDs).