Ultrastable and ultrasensitive pH-switchable carbon dots with high quantum yield for water quality identification, glucose detection, and two starch-based solid-state fluorescence materials
Daiyong Chao, Jinxing Chen, Qingfeng Dong, Weiwei Wu, Desheng Qi, Shaojun Dong
Abstract
It is attractive and encouraging to develop new fluorescent carbon dots (CDs) with excellent optical properties and promising applications prospects. Herein, highly-efficient green emissive CDs (m-CDs) with a high quantum yield (QY) of 71.7% in water are prepared through a facile solvothermal method. Interestingly, the m-CDs exhibit excellent fluorescence stability in the pH range of 1–9. However, the fluorescence intensity of the m-CDs is almost completely quenched as the pH is increased from 9 to 10. The mechanism of the unique pH-responsive behavior is discussed in detail and a plausible mechanism is proposed. Owing to the unique pH-responsive behavior, the m-CDs are used as a on-off fluorescent probe for water quality identification. By combining the reversible pH-ultrasensitive optical properties of the m-CDs in the pH range of 9–10 with the glucose oxidase-mimicking (GOx-mimicking) ability of Au nanoparticles (AuNPs), glucose can be quantitatively detected. Finally, two environment-friendly starch-based solid-state fluorescence materials (powder and film) are developed through green preparation routes.