▎ 摘　　要

NOVELTY - A nitrogen-doped graphene quantum dot is prepared by placing sulfuric acid and phosphorus pentoxide into flask, uniformly stirring and mixing, heating and slowly adding graphite powder, continuously heating, cooling, diluting using distilled water, filtering and repeatedly washing, and drying under nitrogen protection; slowly adding potassium permanganate powder and sulfuric acid, uniformly mixing, slowly adding (A), keeping water bath temperature, uniformly mixing, continuously stirring in water bath, adding distilled water, stirring, adding distilled water, dropwise adding analytically pure hydrogen peroxide, hot filtering, washing precipitate by distilled water, and drying into vacuum drying box; and ultrasonically uniformly homogenizing analytically pure silicon source and (B) in water, transferring mixed solution to PTFE stainless steel reaction kettle, hydrothermal reacting, filtering, dialyzing, and vacuum freeze-drying. USE - Method for preparing nitrogen-doped graphene quantum dot. ADVANTAGE - The method has simple operation. The product has controllable shape, uniformly scattered particle diameter, relative quantum yield of 5.42% and stable fluorescent performance. DETAILED DESCRIPTION - A nitrogen-doped graphene quantum dot is prepared by: (A) placing 10 mL of 98% sulfuric acid and 1 g phosphorus pentoxide into flask, uniformly stirring and mixing, heating and slowly adding 2 g graphite powder to 80-80 degrees C, continuously heating for 6 hours, cooling to room temperature, diluting using distilled water, filtering and repeatedly washing to neutral, and drying under nitrogen protection; (B) slowly adding 6 g potassium permanganate powder and 46 mL of 98 wt.% sulfuric acid under ice bath condition, uniformly mixing, slowly adding (A), keeping water bath temperature at 0-20 degrees C, uniformly mixing, continuously stirring in water bath at 35 degrees C for 4 hours to form brown pasty matter, adding 100 mL distilled water, stirring for 30 minutes, adding 300 mL distilled water, dropwise adding 12 mL analytically pure hydrogen peroxide to bright yellow solution, hot filtering, washing precipitate by distilled water to neutral, and drying into vacuum drying box to obtain graphene oxide solid; and (C) ultrasonically uniformly homogenizing 200-3000 mu L analytically pure silicon source and 10 mL of 0.1-2.0 mg/mL (B) in water, transferring mixed solution to 20-200 mL PTFE stainless steel reaction kettle, hydrothermal reacting at 120-200 degrees C for 4-8 hours, filtering, dialyzing, and vacuum freeze-drying. The silicon source is ammonia water, urea, ammonium hydrogen carbonate and ethylenediamine.