One-step synthesis of robust nitrogen-doped carbon dots: Acid-evoked fluorescence enhancement and their application in Fe³⁺ detection

Robust and highly fluorescent N-doped carbon dots (CDs) are obtained from a hybrid source, alginic acid and ethanediamine. During a hydrothermal process, the raw materials are propelled to form nano-sized particles; these resultant CDs possess desirable functional groups on the particle surface. We have further investigated their optical performance under various pH conditions as well as their capacity for sensing metal ions. The N-doped CDs especially exhibit remarkable acid-evoked fluorescence enhancement under acidic conditions. Finally, the as-prepared CDs are tested for their ability to detect Fe³⁺ in acidic pure water and urban river water media, and the fluorescence-quenching mechanism and recovery properties of the CD/Fe³⁺ mixture are also investigated.