Cranberry Beans Derived Carbon Dots as a Potential Fluorescence Sensor for Selective Detection of Fe³⁺ Ions in Aqueous Solution

Abstract

Recently, synthesis, characterization, and application of carbon dots have received much attention. Natural products are the effectual carbon precursors to synthesize carbon dots with fascinating chemical and physical properties. In this study, the fluorescent sensor of carbon dots derived from cranberry beans without any functionalization and modification was developed. The carbon dots were prepared with a cheap, facile, and green carbon precursor through a hydrothermal treatment method. The synthetic process was toxic chemical-free, convenient, and environmentally friendly. To find the optimized synthetic conditions, the temperature, heating time duration, and carbon precursor weight were evaluated. The prepared carbon dots were characterized by UV light, transmission electron microscopy, Raman, Fourier transform infrared, UV-vis, and fluorescence spectroscopy. The resulting carbon dots exhibit stable fluorescence with a quantum yield of approximately 10.85%. The carbon dots emitted the broad fluorescence emission range between 410 and 540 nm by changing the excitation wavelength and were used for the detection of Fe³⁺ ions at the excitation of 380 nm. It is found that Fe³⁺ ions induced the fluorescence intensity quenching of the carbon dots stronger than other heavy metals and the Fe³⁺ ion detection can be achieved within 3 min. Spectroscopic data showed that the obtained carbon dots can detect Fe³⁺ ions within the wide concentration range of 30-600 μM with 9.55 μM detection limit.