Carbon dots from surface-capping/passivation of small carbon nanoparticles with nanoscale titanium dioxide

Abstract

Carbon dots are classically defined as small carbon nanoparticles (CNPs) with effective surface passivation, which has been accomplished predominantly by surface organic functionalization. In the current work, the passivation is achieved by the surface coating of CNPs with nanoscale TiO₂ for CNP/TiO₂ core/shell nanostructures, which are analogous to conventional semiconductor core/shell quantum dots (QDs). The TiO₂ capping of CNPs results in substantial enhancements in the fluorescence quantum yields, also analogous to the similar enhancements famously known for the semiconductor QDs. Mechanistic implications of the findings, including the associated further validation on the classical definition of carbon dots, are discussed.