Direct one pot synthesis of blue luminescent polymeric carbon dots gel and their application for selective detection of Ag⁺ ions

ABSTRACT

Here, we report, the direct synthesis of fluorescent carbon dots in gel form by hydrothermal reaction of 3-aminopropyltriethoxysilane in the presence of aqueous nitric acid at 300°C. The chemical structure, morphology, rheological and adsorption properties of the silicon containing carbon dots (SiCDs) gel is studied using spectroscopic and microscopic characterization methods. The average fluorescent lifetime of the SiCDs gel was approximately 11 ns, and such high lifetime value is entailed in photo-catalytic and energy conversion applications. Nitrogen adsorption studies revealed that the gel has high nitrogen adsorption tendency, approximately two orders of magnitude higher than that of the conventional CDs. Further, SiCDs gel reduces silver ions (Ag⁺) to Ag nano-particles at ambient temperature without additional reducing agents. The luminescence of CDs was quenched by Ag nano-particles formed on the surface, which is proportional to the concentration of Ag⁺ ions. The sensor shows high selectivity towards Ag⁺ with a sensitivity and dynamic range of 85 nM and 0.4 µM– 0.1 M, respectively.

KEYWORDS:

• Ag⁺ sensing
• Ag nano-particles
• fluorescent carbon dots
• hydrothermal reaction
• polymeric gel

Acknowledgments

Authors acknowledge IIST for funding and IIT Madras for characterization studies.