Benefit of porous silica nanoreactor in preparation of fluorescence carbon dots from citric acid

Abstract

A facile and robust synthesis of carbon dots (CDs) emitting blue-light in water without activation and stabilization has been developed by pyrolysis of citric acid (CA) adsorbed in silica gel (SiO 2 ) pores. Effect of the host pore size on luminescent properties of SiO 2 @CDs nanocomposite as well as water suspension of CDs has been studied. The synthesis conditions such as concentration of the precursor, duration of synthesis also have been investigated. It has been demonstrated that upon the thermal treatment of silica gels saturated with CA (60% of maximum loading) at 170°C for 5-600 min, luminescent CDs are shaped inside the nanoreactor pores. These SiO 2 @CDs emit photoluminescence centered at 450 nm. Silica-immobilized CDs can be separated from the source molecules and sideproducts by centrifugation, which allows avoiding the dialysis of the resulted mixture and so improve the scaling of the synthesis. The CDs can be easily released from SiO 2 @CDs by washing it with water. Water-eluted CDs demonstrate photoluminescence at 447 nm. The smaller pore size of the host and longer time of thermal treatment promote the formation of the CDs with better photoluminescent peak symmetry and higher quantum yield up to 10.1%.

Carbon dots: Types, preparation, and their boosted antibacterial activity by photoactivation. Current status and future perspectives

“…The synthesis by the template method generally uses silicon oxide templates (nanoparticles or mesoporous silicon) that have entrusted spaces, called microreactors, that allow the polymerization of precursor micromolecules under conditions of temperature, pressure, and acid agents. This type of synthesis is reported with a b-u approach due to the size of the templates (Mikhraliieva et al, 2020;Stepanidenko et al, 2022).…”

Carbon dots from eco-friendly precursors for optical sensing application: an up-to-date review

“…However, the top-down synthesis strategies involve harsh experimental conditions, tedious operation steps, extended reaction durations, utilization of costly ingredients and expensive equipments, which greatly limit their practical application. Moreover, the CDs prepared using the top-down strategies without further purification and surface modification generally present weak luminescence and low quantum yield (QY) (Wang and Hu 2014;Mikhraliieva et al 2020).…”

The void side of silica: surveying optical properties and applications of mesoporous silica

“…Another open issue is their exploitation at the solid state since the reported efficient optical features are usually observed by dispersing the CDs in solution [103]. However, the interaction with MS was shown to be beneficial for these benign nanomaterials, both regarding their synthesis [104] or the tuning of their optical properties for photonics [64], sensing [105], bioimaging [106], disease detection [107], and cancer therapy [106]. As for the photonics applications, by changing the acid reacting with o-phenylenediamine (oPD) in an ethanol-based solvothermal synthesis a palette of CDs emitting at different emission wavelengths across the visible range was obtained and exploited to prepare a white light emitting diode prototype by properly mixing those CDs into a silica sol-gel [64].…”