A comparison of fluorescent N-doped carbon dots supported on the surface of hollow and solid carbon spheres, and solid silica spheres

Abstract Fluorescent carbon dots (Cdots) have attracted many researchers due to their strong optical photoluminescence (PL) properties; however, due to their small size they agglomerate in the solid state which makes it difficult to remove them from solution. To overcome these problems, Cdots can be deposited on a support, but to date, few systematic studies of Cdots-support systems have been reported, especially those on carbon supports. Herein, we report a systematic study of the effect of the use of N-Cdots (5, 10, 15 and 20%) supported on the surface of hollow carbon spheres (HCSs), solid carbon spheres (SCSs) and silica spheres (SSs). The morphology of the Cdots and their composites (Cdots/SSs, Cdots/HCSs and Cdots/SCSs) was studied by TEM, TGA, XRD, FTIR, UV–vis and PL techniques. The FTIR, XRD and TGA data suggest different interactions of the Cdots with the supports. The PL quantum yield for bare Cdots was 34% and this value was dependent on the supports, in the order Cdots/SSs > Cdots/HCSs > Cdots/SCSs due to different interactions between the Cdots and the support.