DMF-mediated synthesis of N,S-co-doped carbon quantum dots and their fluorescence quenching mechanism toward Hg ²⁺ via surface complexation

Nitrogen and sulfur co-doped carbon quantum dots (N,S-CQDs) were synthesized via a green, one-step hydrothermal method using waste lemon peel as the carbon source and glutathione (GSH) as the N,S dopant in a dimethylformamide (DMF) medium.