Table 3. UV–Vis Spectra Peaks, PLE Peaks, Excitation Peak from Tauc Plot and Band Gap for GQD1–GQD4.

	GQD1	GQD2	GQD3	GQD4
π → π* (nm)	261	279	253	254
n → π* (nm)	357	370	365	325
PLE (nm)	354, 370	343, 368	359, 376	361, 403
excitation peaks (nm)	349	340	363	328
band gap (eV)	3.55	3.64	3.41	3.78