Fluorescent Carbon Quantum Dots with Fe(III/II) Irons as Bridge for the Detection of Ascorbic Acid and H2O2

Abstract

Nitrogen-sulfur co-doped carbon quantum dots (N, S-CQDs) with good photoluminescence properties were prepared by hydrothermal method using citric acid (CA) and methionine (Met) as precursors. Co-doping with N and S facilitates the electron transfer rate and coordination interaction between N,S-CQDs and Fe(III) ions which acts as a quencher of fluorescence. Based on a simple redox principle, a highly sensitive and selective method for the detection of ascorbic acid (AA) and H2O2 was successfully developed. The calibration curves obtained are linear for the current versus AA and H2O2 concentration over the range 50-500μM and 10-140μM, respectively. And the detection limits for AA and H2O2 are 4.2μM and 1.9μM, respectively. The quantitative analysis of AA and H2O2 in various juices and H2O2 disinfectant with Fe3+/CQDs or Fe2+/CQDs gave the recoveries of 87.8%-117.5% and 99.2%-106.4% with relative standard deviations (RSD) of 1.6-5.1% and 1.7-3.1%, respectively, showing satisfactory results for the determination of AA and H2O2 in actual application. The proposed strategy may provide a new pathway to developing inexpensive and sensitive way for the detection of various redox reaction-involved system.