Nanopore array derived from L-cysteine oxide/gold hybrids: Enhanced sensing platform for hydroquinone and catechol determination

In this contribution, the nanopore array derived from L-cysteine oxide/gold hybrids (NA-COGH) was applied to the simultaneous determination of hydroquinone (HQ) and catechol (CT). NA-COGH was prepared by a sequential electrodeposition of L-cysteine oxide and gold into the voids of polystyrene spheres template, followed by removing the template using tetrahydrofuran. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analyses validated the formation of NA-COGH on the glassy carbon electrode. The charge transfer ability of NA-COGH was studied by means of scanning electrochemical microscopy (SECM). A better charge transfer rate was obtained by optimizing the electrodeposition conditions. More interestingly, the as-prepared NA-COGH presents high electrocatalytic activity for the oxidation of HQ and CT. The sensing platform based on NA-COGH shows a wide linear response for HQ and CT in the concentration range of 4.0 x 10(-7)-6.0 x 10(-4) M and 8.0 x 10(-7)-5.0 x 10(-4) M, with detection limit of 1.9 x 10(-8) M and 3.4 x 10(-8) M (S/N = 3), respectively. Rotating disk electrode experiments revealed that the catalytic rate constants were as high as 7.99 x 10(-3) cm s(-1) and 7.38 x 10(-3) cm s(-1) at potential of 302 mV and 416 mV for HQ and CT, respectively. With good stability and reproducibility, we applied the present method to the simultaneous determination of HQ and CT in tap water and lake water. These results indicate that NA-COGH is a promising electrode material with great potential in electrocatalysis and electrochemical sensing. (C) 2012 Elsevier Ltd. All rights reserved.