Sensitive pH probe developed with water-soluble fluorescent carbon dots from chocolate by one-step hydrothermal method

ABSTRACT

In present work, fluorescent carbon dots (CDs) with an average diameter of 2.5 nm were firstly synthesised by a simple, convenient and low-cost hydrothermal method from chocolate. The obtained CDs possessed fine monodispersity and bright blue fluorescence that was strongest at an excitation wavelength of 360 nm and had a comparable quantum yield of 12% (in case of dots prepared in presence of nitric acid). The emission peak depended on the excitation wavelength in the range from 320 to 440 nm. Ionic strength had a weak effect up to 1.0 M and then no significant change was found in the range of 1.0–4.5 M. The fluorescence intensity of CDs displayed good pH adaptability and a linear dependence on the pH change in the range of pH 1.0–3.0 and pH 9.0–12.5, which have promising potentials for pH sensor.

KEYWORDS:

• Chocolate
• carbon dots
• fluorescence
• pH sensor

Acknowledgements

This work was supported by the National Natural Science Foundation of China (21377167).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [21377167].