Partic. vol. 41 pp. 94-100 (December 2018)
doi: 10.1016/j.partic.2017.12.009

N-doped carbon quantum dots as fluorescent probes for highly selective and sensitive detection of Fe³⁺ ions

Xiangyi Deng^a, Yali Feng^a,*, Haoran Li^b,*, Zhuwei Du^b, Qing Teng^a, Hongjun Wang^a

ylfeng@ustb.edu.cnhrli@ipe.ac.cn

Abstract

To investigate the effect of nitrogen on the photoluminescence properties of carbon quantum dots (CQDs), N-doped carbon quantum dots (N-CQDs) were synthesized by one-step hydrothermal treatment using biomass tar as the carbon precursor. As an inevitable organic pollutant, the unsaturated bonds in biomass tar, such as carboxylic acids, aldehydes, and aromatics, are favorable for formation of the graphitic carbon lattice. The obtained N-CQDs are spherical with an average particle size of 2.64 nm and the crystal lattice spacing is 0.25 nm, corresponding to the (100) facet of graphitic carbon. The N-CQDs emit bright blue photoluminescence under 365 nm ultraviolet light, and they have excellent water solubility and stability with a high quantum yield of 26.1%. Coordination between the functional groups on the N-CQD surface and Fe³⁺ ions is promoted because of the improved electronic properties and surface chemical reactivity caused by N atoms, leading to a significant fluorescence quenching effect of the N-CQDs in the presence of Fe³⁺ ions with high selectivity and sensitivity. There is a linear relationship between ln (F₀/F) and the Fe³⁺ concentration in the N-CQD concentration range 0.06–1400 μmol/L with a detection limit of 60 nmol/L, showing that the N-CQDs have great potential as a fluorescent probe for Fe³⁺ detection.

Graphical abstract

Keywords

N-doped carbon quantum dots; Fe³⁺ ion detection; Fluorescence quenching; Biomass tar