Facile fabrication of boron and nitrogen co-doped carbon dots for “ON–OFF–ON” fluorescence sensing of Al3+ and F− ions in water samples

• Published in: RSC advances Vol. 13; no. 34; pp. 23736 - 23744
• Main Authors: Alqahtani, Yahya S, Mahmoud, Ashraf M, Mahnashi, Mater H, Ramadan, Ali, Shahin, Reem Y, El-Wekil, Mohamed M, Batakoushy, Hany A
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 04.08.2023; The Royal Society of Chemistry
• Subjects: Boron; Caffeine; Carbon dots; Chemistry; Ecological effects; Emission; Fluorescence; Ion concentration; Nitrogen; Switches; Water sampling
• ISSN: 2046-2069
• DOI: 10.1039/d3ra02919k

Water contamination with harmful ions has grown to be a significant environmental issue on a global scale. Therefore, the fabrication of simple, cost-effective, and reliable sensors is essential for identifying these ions. Herein, co-doping of carbon dots with new caffeine and H3BO3-derived boron (B) and nitrogen (N) was performed (BN@CDs). The as-prepared BN@CDs probe was used for the tandem fluorescence sensing of Al3+ and F− based on “ON–OFF–ON” switches. The BN@CDs nanoswitch has a high quantum yield of 44.8% with λexc. and λem. of 360 nm and 440 nm, respectively. The probe exhibited good stability with different pH, ionic-strengths, and irradiation times. The fluorescence emission of BN@CDs was decreased as the Al3+ concentration was increased with a linear range of 0.03–90 μM and a limit of detection (S/N = 3) equal to 9.0 nM. Addition of F− restored the BN@CDs emission as F− ions form a strong and stable complex with Al3+ ions [Al(OH)3F]−. Therefore, the ratio response (F/F°) was raised by raising the F− ion concentration to the range of 0.18–80 μM with a detection limit (S/N = 3) of 50.0 nM. The BN@CDs sensor exhibits some advantages over other reported methods in terms of simplicity, high quantum yield, and low detection limit. Importantly, the sensor was successfully applied to determine Al3+ and F− in various ecological water specimens with accepted results.