Green synthesis of value-added nitrogen doped carbon quantum dots from Crescentia cujete fruit waste for selective sensing of Fe3+ions in aqueous medium

Green synthesis of nitrogen-doped carbon quantum dots (N-CQDs) by one-pot hydrothermal synthesis was re-ported using Crescentia cujete fruit waste for the first time in this study. The spherical carbon dots obtained are loaded with carboxyl, hydroxyl and amino functional groups on their surface which make them highly dispersible in water and emit green fluorescent light under UV irradiation. The photoluminescence (PL) behaviour of N-CQDs is greatly reduced by Fe3+ ions because of strong excited state electron transfer. This fluorescent turn-off behaviour towards Fe3+ is highly selective and sensitive with a limit of detection (LOD) of 0.257 mu M. The highly stable N-CQDs were also successfully used as promising fluorescent probes for the sensitive detection of Fe3+ ions in three real waters, namely, river water, laboratory water and tap water.

Automated summary

Green synthesis of nitrogen-doped carbon quantum dots (N-CQDs) was achieved for the first time using Crescentia cujete fruit waste. The resulting N-CQDs are spherical in shape and exhibit high dispersibility in water, emitting green fluorescent light under UV irradiation. The fluorescence of N-CQDs is significantly quenched by Fe3+ ions, indicating strong electron transfer. The highly stable N-CQDs were successfully used as fluorescent probes for the sensitive detection of Fe3+ ions in three different water sources.