A Facile Approach to the Hydrothermal Synthesis of Silica Nanoparticle/Carbon Nanostructure Luminescent Composites

Abstract

Luminescent carbon nanostructures (CNSs) have been intensively researched, but there is still no consensus on a fundamental understanding of their structure and properties that limits their potential applications. In this study, we developed a facile approach to the synthesis of luminescent composite SiO2 nanoparticles/CNSs by the targeted formation of a molecular fluorophore, as the significant luminescent component of CNSs, on the surface of a silica matrix during a one-stage hydrothermal synthesis. Silica nanoparticles were synthesized by reverse microemulsion and used as a matrix for luminescent composites. The as-prepared silica nanoparticles had a functional surface, a spherical shape, and a narrow size distribution of about 29 nm. One-stage hydrothermal treatment of citric acid and modified silica nanoparticles made it possible to directly form the luminescent composite. The optical properties of composites could be easily controlled by changing the hydrothermal reaction time and temperature. Thus, we successfully synthesized luminescent composites with an emission maximum of 450 nm, a quantum yield (QY) of 65 ± 4%, and an average size of ~26 nm. The synthesis of fluorophore doped composite, in contrast to CNSs, makes it possible to control the shape, size, and surface functionality of particles and allows for avoiding difficult and time-consuming fractionation steps.

One-pot hydrothermal synthesis of fluorophore-modified cerium oxide nanoparticles

“…34,35 For the synthesis of IPCA temperature, processing time, and reagent ratio can be varied. 33,35,38,45 In our previous study it was found that during hydrothermal synthesis at 180 1C for 3 hours 37 and a ratio of CA to EDA of 1 : 1.5, 46 the molecular fluorophore IPCA is formed as the main product. In this regard, we used these conditions to obtain CeO 2 NPs modified by IPCA (CeO 2 -IPCA NPs).…”

“…It is known that IPCA obtained by the hydrothermal method from CA and EDA has a relatively high quantum yield of 460%. 32,37,46 CeO 2 -IPCA NPs obtained at a Ce 3+ to CA ratio of 1 : 3 have a QY of 62 AE 2%, comparable to the molecular fluorophore IPCA. Samples with other ratios are characterized by a lower QY (Table 1).…”

“…[34][35][36] This fluorophore can be in an unbound state or be associated with various structures by non-covalent or covalent bonds. 37,38 The binding of IPCA to various surfaces results in a high and stable fluorescence.…”

Fluorescent Alloyed CdZnSeS/ZnS Nanosensor for Doxorubicin Detection

“…The relative QY of QD emission was calculated as described in [ 31 ], relative to fluorescent dye Coumarin 153 (ethanol solution, peak optical density 0.1, QY 53%). The excitation and emission wavelengths of the QY measurement were 360 and 514 nm, respectively.…”