One-step hydrothermal synthesis and optical properties of self-quenching-resistant carbon dots towards fluorescent ink and as nanosensors for Fe detection.

In our work, blue photoluminescent N-doped carbon dots (CDs) were developed a green and simple hydrothermal method with citric acid and polyvinyl pyrrolidone (PVP K-30) as the carbon source and the nitrogen source, respectively. The as-prepared CDs have a high fluorescent quantum yield of 30.21% and considerable luminescence stability. The fluorescence intensity of the CDs was found to be effective quenched when adding Fe ions to the CDs solution. The quenching phenomenon can be used to detect Fe ions within a linear range of 0-300 μM with a detection limit of 45.5 nmol L, which suggested its potential application in the detection of Fe ions. At the same time, we also noted the excellent self-quenching-resistant property of the as-prepared CDs in the solid state, and bright blue fluorescence was observed under UV excitation. What's more, the as-prepared CDs can also be used as fluorescent ink and were presented under UV excitation.