摘要: Absorption and emission properties of oxidized graphene quantum dots (GQDs) and amino functionalized GQDs (NG) were explored by B3LYP method combined with 6-31G (d) basis set. The oxygen- and nitrogen-containing groups can tune the intensity as well as the wavelength of absorption and emission. The groups such as hydroxyl, carboxyl, amino, amide, and pyridine-like N can appropriately lengthen the absorption and emission wavelength of GQDs. However, the carbonyl group, graphitic-like N, and pyrrolic-like N obviously decrease the oscillator strength and lengthen the emission wavelength of GQDs out of the visible region. The lowest excited state S₁ of NG has the strongest emission in investigated complexes, which indicates that it is an excellent luminous material. The theoretical investigations verify that the oxygen- and nitrogen-related groups can tune the luminescence of GQDs. The fluorescence quenching of GQDs reduced by ammonia mainly depends on the graphitic-like and pyrrolic-like N.