Síntese, caracterização e aplicações dos carbon dots autodopados com enxofre e nitrogênio

Abstract

At first considered just an impurity resulting from the synthesis of another nanomaterial, carbon quantum dots have been increasing their space in several scientific areas. Whether due to its small size, low cytotoxicity, luminescent property, easy synthesis, low cost and solubility in water, it soon gained varied applications. Being the youngest nanomaterial of the carbon family, there is still much to understand regarding the mechanisms, properties and possibilities of applications. The most important property of carbon quantum dots, which led to their discovery, is fluorescence, and it is on this that investigations are based. In this work a single and simple pathway synthesis was presented, through the hydrothermal synthesis process, using cysteine as a precursor material, which results in carbon quantum dots self-doped with oxygen, nitrogen and sulfur. Subsequently, sensitivity was characterized and evaluated against different pHs, showing an efficient sensitivity between pHs 2 to 9, with the possibility of application in real samples, and promoting control of its luminescent properties. This variation was well characterized, showing a change not only in the intensity but also in the emission wavelength of the luminescence. Using various techniques, we were able to understand the causes of this effect. Rapid test devices were also made for water pH analysis and forensic tests for digital marking. Carbon quantum dots were also used as a possible probe for identifying critical micellar concentrations (CMCs) of amphiphilic monomers (surfactants).