3D-Flower-Like Copper Sulfide Nanoflake-Decorated Carbon Nanofragments-Modified Glassy Carbon Electrodes for Simultaneous Electrocatalytic Sensing of Co-existing Hydroquinone and Catechol.

A copper sulfide nanoflakes-decorated carbon nanofragments-modified glassy carbon electrode (CuS-CNF/GCE) was fabricated for the electrocatalytic differentiation and determination of hydroquinone (HQ) and catechol (CC). The physicochemical properties of the CuS-CNF were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy. The electrocatalytic determination of HQ and CC over the CuS-CNF/GCE was evaluated by cyclic voltammetry and differential pulse voltammetry. An excellent detection limit and sensitivity of the CuS-CNF/GCE are obtained (0.293 µM and 0.259 µM) with a sensitivity of 184 nA µM-1 cm-2 and 208 nA µM-1 cm-2 (S/N=3) for HQ and CC, respectively. In addition, the CuS-CNF/GCE shows a selective identification of HQ and CC over potential interfering metal ions (Zn2+, Na+, K+, NO3-, SO42-, Cl-) and organic compounds (ascorbic acid, glucose), and a satisfactory recovery is also obtained in the spiked water samples. These results suggest that the CuS-CNF/GCE can be used as an efficient electrochemical sensor for the simultaneous determination of co-existing environmental pollutants such as HQ and CC in water environments with high selectivity and acceptable reproducibility.

The simultaneous electrochemical detection of catechol and hydroquinone with [Cu(Sal-ß-Ala)(3,5-DMPz)2]/SWCNTs/GCE.

A glassy carbon electrode was modified with a copper(II) complex [Cu(Sal-ß-Ala) (3,5-DMPz)2] (Sal = salicylaldehyde, ß-Ala = ß-alanine, 3,5-DMPz = 3,5-dimethylpyrazole) and single-walled carbon nanotubes (SWCNTs). The modified electrode was used to detect catechol (CT) and hydroquinone (HQ) and exhibited good electrocatalytic activities toward the oxidation of CT and HQ. The peak currents were linear with the CT and HQ concentrations over the range of 5-215 µmol·L(-1) and 5-370 µmol·L(-1) with corresponding detection limits of 3.5 µmol·L(-1) and 1.46 µmol·L(-1) (S/N = 3) respectively. Moreover, the modified electrode exhibited good sensitivity, stability and reproducibility for the determination of CT and HQ, indicating the promising applications of the modified electrode in real sample analysis.