The influence of PH on the properties of carbon dots with different surface functionalization: sizes and photoluminescence quantum yield

In this work carbon dots synthesized by the hydrothermal method and subsequent functionalization of the surface with carboxyl and hydroxyl groups were explored. As a result of studying the optical and colloidal properties of monofunctionalized carbon dots, a significant effect of the acidity of the nanoparticle environment on them was found. It has been found that for the photoluminescence quantum yield of carbon dots the greatest changes occur in the pH range from 2 to 5 for carbon dots with carboxyl surface groups and from 8 to 12 for carbon dots with hydroxyl groups. The mechanisms of the influence of surface functional groups on the photoluminescence of carbon dots with a change in the pH of the suspension are proposed.