N-doped carbon quantum dots obtained from citric acid and L-phenylalanine

Hydrophobic N-doped carbon quantum dots (N-CQDs) were prepared using citric acid and L-phenylalanine through hydrothermal synthesis at optimum conditions (temperature T = 200 °C and time t = 9 h) and thoroughly investigated with different techniques. In organic solvents (ethanol, chloroform, dimethyl formamide, and xylene) under 350 nm excitation wavelength, N-CQDs exhibit intensive blue photoluminescence (PL) with the quantum yield equal to 36.5 %. Being embedded into polymer matrices (poly(methyl methacrylate) and epoxy resin), N-CQDs preserved their high PL.