Na+：The key to ultra-long afterglow lifetime of CDs in dense SiO2 matrices

Abstract

The carbon-dot-based room-temperature phosphorescence has emerged as a shining new star in the carbon nanomaterial family in recent years due to its excellent optical properties. However, there still exists a significant challenge in obtaining carbon dots (CDs) with ultra-long phosphorescenc0 lifetimes. In this study, tetraethyl orthosilicate (TEOS) was used to achieve the in-situ growth and encapsulation of CDs in a 3D SiO2 network through a one-pot hydrothermal method. It was demonstrated that Na+ is a key factor to achieve the ultra-long afterglow lifetime of CDs in dense SiO2 matrices, and the introduction of Na+ has a significant effect on extending the afterglow lifetime of various CDs. The designed Na/CDs@SiO2 nanomaterial exhibited an ultra-long afterglow lifetime of 6.69 s, which surpassed most reported CDs-based afterglow lifetimes. This work provides a design principle and general strategy for achieving ultra-long afterglow lifetimes of CDs in dense SiO2. Based on the stable photoluminescent (PL) property, low biotoxicity, and ultra-long afterglow lifetime of Na/CDs@SiO2 nanomaterial, it was successfully applied in imaging Hela cells.