Nanoparticles’ environment, in particular pH, can strongly affect their photoluminescence (PL). This can be especially true for the surface PL of nanodiamonds (NDs) known to be dependent on the composition of surface groups. In this paper, the effect of environmental pH in the range from 2 to 12.5 on the surface photoluminescence of oxidized NDs of various syntheses and surface treatments was investigated. For the first time, the varying changes of the NDs’ PL with the pH were shown, having, however, an essential common feature: they were observed in the same pH regions from 2 to 5 and from 9 to 12.5, while in the pH region from 5 to 9, the PL intensity of all samples was almost constant. Obtained dependences of NDs’ ζ-potentials on pH and quantum mechanical modeling showed that all changes of NDs’ PL are due to the (de)protonation of surface groups: carboxyl at pH from 2 to 5 and hydroxyl on sp2-hybridized carbon at pH from 9 to 12.5. The varying response of NDs’ PL to such deprotonation shows the possibility of tuning the surface photoluminescence of NDs for use in industry and biomedicine beyond what is possible by only controlling the nanodiamonds’ surface groups.
In this paper photoluminescence properties of aqueous suspensions of carbon nanoparticles (nanodiamonds, carbon dots and complexes on their basis) with different ratio of surface carbon in sp 3 -and sp 2 -hybridizations were studied by methods of Raman, fluorescence and IR absorption spectroscopy. It was found that intensity of photoluminescence correlates with amount of carbon in non-diamond phase on the surface of nanoparticles. Nanoparticles with high non-diamond carbon phase content revealed more intense photoluminescence. The obtained results support the hypothesis about surface nature of photoluminescence of nanodiamonds and carbon dots.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.