Kilogram-scale fabrication of TiO2 nanoparticles modified with carbon dots with enhanced visible-light photocatalytic activity.

Incorrect discharge of dye wastewater will cause environment pollution and be very harmful to human health. Visible-light photocatalysis over large-scale synthesized semiconductor materials can become one of the feasible solutions for the practical application of purifying dye wastewater. As a new candidate, carbon dots (CDs) with unique fluorescence were fabricated on a tens of grams scale and then further applied to the kilogram-scale synthesis of a CDs/TiO2 composite by one-step heat treatment. Compared with single TiO2 nanoparticles (NPs), the CDs/TiO2 composite with a large specific surface area exhibits enhanced photo-degradation performance for methyl orange (MO). This phenomenon can be attributed to the loading of CDs in the TiO2 NPs, which is conducive to broadening the light absorption spectrum and improving absorption intensity, narrowing the band gap, charge carrier trapping, up-converting properties, and charge separation. The kilogram-scale synthesis of the CDs/TiO2 photocatalyst does not affect the morphology, structure, optical properties and photocatalytic performance of the composite, which opens up a new avenue to construct elaborate heterostructures for enhanced photocatalytic performance using visible light as the light source.