In this work, the metal (Zn, Co) and non-metal (N) co doped carbon quantum dots (Zn/Co-NCDs) was prepared by hydrothermal method, and characterized by FT-IR, TEM and XPS. It was found that bimetal doped could effectively improve the quantum yield (QY) of carbon quantum dots. The presence of Fe(III) could ''turn off'' the fluorescence signal, and the addition of ascorbic acid (AA) could ''turn on'' the fluorescence signal. An ''on-off-on'' fluorescent probe based on Zn/ Co-NCDs for Fe(III) and AA analysis was established. The liner ranges were 0.03–20.00 μg/mL and 0.69–20.00 μg/mL with the LODs of 0.010 μg/mL and 0.23 μg/mL, respectively. The method was successfully applied to the determination real samples with satisfactory results.
