title: Electrolyzing synthesis of boron-doped graphene quantum dots for fluorescence determination of Fe3+ions in water samples.
abstract: This work reports a facile electrolyzing method to synthesize boron-doped graphene quantum dots (BGQDs) and uses the BGQDs as a fluorescent probe to determine Fe3+ion levels in water samples. The BGQDs were produced by oxidizing graphite in an aqueous borax solution at pH 7; then, the borate solution was filtered with BGQDs, and the borate was dialyzed from the filtrate, leaving a solution of BGQDs in water. The amount of the B in the BGQDs can be adjusted by changing the concentration of borax used for the electrolyte. The excitation wavelength- and B amount-dependent fluorescence characteristics of BQGDs were studied. The fluorescence intensity of the BGQDs is measurable in real time, and its quenching is very sensitive to the concentration of Fe3+ions in the system but not to other possible coexisting metal ions. The fluorescence quenching mechanism of Fe3+ions to BGQDs is studied and explained based on electrochemical voltammetry and DFT simulations. The analytical signal, which is defined as F0/F, where F0and F are the fluorescence intensities of the BGQDs before and after interaction with Fe3+ions, respectively, displays a good linear relationship in the Fe3+ion concentration range of 0.01-100µm with a correlation coefficient of 0.999 and a limit of detection (LOD) of ~(0.005±0.001) μM. The LOD value is much lower than the water quality standards for Fe3+ions (0.3ppm, ~5.36µm) in drinking water suggested by the WHO (World Health Organization) and EPA (U.S. Environmental Protection Agency), implying that this method has great potential for applications in real sample assays. For example, the determination of the Fe3+ion levels in three water samples (tap water, groundwater, and lake water) gives approximately the same results as those determined by the EPA-recommended AAS (atomic adsorption spectroscopy) method.
authors.affiliation: Jiangsu Key Laboratory of New Power Batteries, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, National and Local Joint Engineering Research Center of Biomedical Functional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, PR China.
authors.forename: Li
authors.initials: L
authors.lastname: Chen
authors.affiliation: Jiangsu Key Laboratory of New Power Batteries, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, National and Local Joint Engineering Research Center of Biomedical Functional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, PR China.
authors.forename: Chuanli
authors.initials: C
authors.lastname: Wu
authors.affiliation: Jiangsu Key Laboratory of New Power Batteries, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, National and Local Joint Engineering Research Center of Biomedical Functional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, PR China.
authors.forename: Pan
authors.initials: P
authors.lastname: Du
authors.affiliation: Jiangsu Key Laboratory of New Power Batteries, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, National and Local Joint Engineering Research Center of Biomedical Functional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, PR China.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Feng
authors.affiliation: Jiangsu Key Laboratory of New Power Batteries, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, National and Local Joint Engineering Research Center of Biomedical Functional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, PR China. Electronic address: wuping@njnu.edu.cn.
authors.forename: Ping
authors.initials: P
authors.lastname: Wu
authors.affiliation: Jiangsu Key Laboratory of New Power Batteries, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, National and Local Joint Engineering Research Center of Biomedical Functional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, PR China. Electronic address: cxcai@njnu.edu.cn.
authors.forename: Chenxin
authors.initials: C
authors.lastname: Cai
keywords: Boron-doped graphene quantum dots; Electrochemical synthesis; Fe(3+) ion detection; Fluorescence quenching; Water sample