High quantum yield photoluminescent N-doped carbon dots for switch sensing and imaging.

Stable blue fluorescent nitrogen doped carbon dots (N-CDs) with a very high quantum yield up to 81% has been reported for the first time. Novel N-CDs were synthesized through an efficient and rapid one-step hydrothermal synthesis process from diethylenetriamine as nitrogen source and a novel carbon source trans-aconitic acid. The nanosized particles of N-CDs were in the range of 2–8 nm and uniformly distributed in molecular level. The N-CDs showed high selectivity toward Fe 3+ with low detection limit of 10.42 nmol L −1 (with corresponding linear range of 2–50 μmol L −1 ) enabling them for ion detection application and also exhibited high fluorescence stability in extreme pH conditions. Novel N-CDs also presented a green emission shift under acidic condition (pH~2) which makes them a potential sensing probe for security papers, food packaging and bio-medical detection sensors. A security paper sensor device has been fabricated and its operation function has been validated by making real time detection of color. The novel and facile to manufacture carbon dots has potential applications ranging from biological nano-sensors for security document to color-switch sensing and bio-imaging. The nitrogen-doped carbon dots synthesized from diethylenetriamine and trans-aconitic acid with a very high quantum yield of 81% provided high photoluminescence properties and good sensitivity and selectivity for Fe 3+ detection. They also presented color switching in high acidic media enabling them to be used as pH sensor and security ink. • Synthesizing of N-CDs through rapid one-step hydrothermal method from diethylenetriamine and trans-aconitic acid. • Significantly high quantum yield up to 81% and good photoluminescence behavior under UV light for prepared carbon dots. • N-CDs as potential probes for sensors and bio-imaging applications due to high selectivity and sensitivity toward Fe 3+ . • Fabricating a security paper sensor device by N-CDs due to their ability of color switching under acidic media.