Effect of temperature on photoluminescence of nanodiamonds and carbon dots in aqueous suspensions

Carbon nanoparticles – carbon dots and nanodiamonds – possess characteristic broadband photoluminescence, which depends on their functional surface groups. Such photoluminescence also depends on the properties of the environment of nanoparticles – the polarity of the solvent, the pH value, and the possible adsorption of ions and macromolecules. However, the nature of the surface photoluminescence of nanodiamonds and of the photoluminescence of carbon dots, as well as the mechanisms of the surrounding molecules' influence on it are currently not fully known. This work is devoted to the study of the effect of temperature on the surface photoluminescence of carboxylated carbon nanoparticles in aqueous suspensions. A similarity between the temperature dependences of the photoluminescence of nanodiamonds and carbon dots was found, and an explanation was proposed for the observed changes in photoluminescence.