Dear Sister:

Strong oxidizing acids carbonize small organic molecules to carbonaceous materials, which can be further cut into small sheets by controlled oxidation.

Peng and Travas-Sejdic reported a simple route to prepare luminescent CQDs in an aqueous solution by dehydrating carbohydrates with concentrated H2SO4, followed by breaking the carbonaceous materials into individual CQDs with HNO3.

Preparation of CQDs via the electrochemical carbonization of low-molecular-weight alcohols is proposed by Zhang and co-workers.

For further detail study the manuscript given in attachment