Fluorescent N-doped carbon quantum dots: A selective detection of Fe3+ and understanding its mechanism

[Display omitted] •Highly fluorescent carbon quantum dot with average size ∼ 3–6 nm have been synthesized successfully by simple methode.•The high fluorescence quenching ability towards heavy metal ions of Fe3+ was observed.•The average lifetime of (5.89648 ± 0.40) ns was calculated from TRPL decay curve.•Deep study on analysis of mechanism behind Fe3+ sensing.•The synthesized N-CQDs shows 80% photostability after 4 h continuous UV (365 nm) illumination. Carbon quantum dots (CQDs) based sensor has been built many times. Optical properties, such as optical absorption, have been neglected for too long. Here, we have reported the luminescence of blue-emitting nitrogen-doped carbon quantum dots (N-CQDs) with average particle size 3–6 nm, synthesized via a simple hydrothermal method, which give intense blue emission under 340 nm excitation wavelengths. As the fluorescence of N-CQDs can be efficiently quenched by Fe3+, the N-CQDs can be constructed as a sensor system for Fe3+ with good sensitivity and selectivity. Effective detection and quantification of Fe3+ at as little as 0.07 µM and 0.22 µM is achieved.