Formation mechanisms and fluorescence properties of carbon dots in coal burning dust from coal fired power plants

TL;DR

This study investigates how carbon dots form in coal burning dust from power plants, explores their fluorescence properties, and suggests environmentally friendly recycling methods for mass production.

Contribution

It identifies two formation mechanisms of carbon dots in coal dust and characterizes their fluorescence, offering insights for sustainable production and environmental protection.

Findings

Two main formation mechanisms identified: self-assembly of polycyclic aromatic hydrocarbons and breaking of bridge bonds.

Carbon dots emit purple fluorescence around 410 nm under violet and red light excitation.

Up-conversion fluorescence is due to a two-photon absorption process.

Abstract

Carbon dots (CDs) shows great application potential with their unique and excellent performances. Coal and its derivatives are rich in aromatic ring structure, which is suitable for preparing CDs in microstructure. Coal burning dust from coal-fired power plants can be utilized as a rich resource to separate and extract CDs. It has been shown in our results that there have two main possible mechanisms for the formation of CDs in coal burning dust. One is the self-assembly of polycyclic aromatic hydrocarbons contained in coal or produced by incomplete combustion of coal. The other mechanism is that the bridge bonds linking different aromatic structures in coal are breaking which would form CDs with different functional groups when the coals are burning at high temperature. Under violet light excitation at 310-340 nm or red light at 610-640 nm, CDs extracted from coal burning dust can emit purple fluorescence around 410 nm. The mechanism of up-conversion fluorescence emission of CDs is due to a two-photon absorption process. The recycling of CDs from coal burning dust from coal-fired power plants are not only good to protect environment but also would be helpful for mass production of CDs.