Green synthesis of biomass-derived carbon quantum dots as fluorescent probe for Fe3+ detection

Eco-friendly synthesis of Carbon quantum dots (CQDs) in water is reported, exploiting various typical crop biomasses as carbon sources. The resultant CQDs exhibit strong fluorescence, good dispersion in common solvents and uniformly dispersed particle size. The synthesized CQDs are highly dispersible in water, due to the presence of surface hydroxyl and carboxyl groups. The CQDs suspension exhibits strong blue fluorescence under UV irradiation, with an optimal excitation wavelength in the range from 350 to 390 nm, which varies with the change of CQD concentration. The emission corresponds to two band transitions, which are originated from pi -> pi* of C-C bonds and n -> pi* of C-O bonds, respectively. Due to its strong fluorescence and energy transfer, the synthesized CQDs materials can be used as a fluorescent probe for the detection of Fe3+ ions with good selectivity and sensitivity, within the Fe3+ concentration range of 0-500 mu M. The research is of significance for converting crop waste to high added-value products, and the obtained CQDs with selective Fe3+ ions determination ability are attractive for the environmental monitoring and medical diagnosis.