In situ immobilization of CuO on SiO\u3csub\u3e2\u3c/sub\u3e/graphite matrix, modified with benzimidazolium-1-acatate ionic liquid: Application as catechol sensor

© 2017 Carbon ceramic material (SiO2/C) was prepared using the sol-gel technique. Copper oxide was in situ synthesized on the pores of the matrix, to ensure homogenous distribution of the electroactive species in the matrix pores. To enhance the conductivity of material, the SiO2/C/CuO was modified with benzimidazolium-1-acetate ionic liquid. The surface area (SBET 432.56 m2/g) and pore volume (0.90 cm3/g) of the material were calculated from BET analysis. SEM images showed compactness of materials, having no phase segregation within the magnification used. The structure of ionic liquid was confirmed using NMR and FTIR analysis. The electrodes as a pressed disk fabricated from SiO2/C, SiO2/C/CuO, and SiO2/C/CuO/IL materials were tested as an electrochemical sensor for catechol determination. Electrochemical impedance spectroscopy has revealed that the SiO2/C/CuO/IL-based sensor assists the charge transfer owing to electron rich density, resonance, and conductance of ionic liquid structural moiety. SiO2/C/CuO/IL electrode exhibits excellent sensitivity, linear response range and low limit of detection (LOD) of 712 μA μmol− 1 dm3 cm− 2, 0.2 mM–10 mM and 0.7 × 10− 8 mol L− 1, respectively. The sensor was also tested for the determination of catechol in real samples and gives very good results for its determination

Nonenzymatic amperometric dopamine sensor based on a carbon ceramic electrode of type SiO\u3csub\u3e2\u3c/sub\u3e/C modified with Co\u3csub\u3e3\u3c/sub\u3eO\u3csub\u3e4\u3c/sub\u3e nanoparticles

© 2019, Springer-Verlag GmbH Austria, part of Springer Nature. An amperometric nonenzymatic dopamine sensor has been developed. Cobalt oxide (Co3O4) nanoparticles were uniformly dispersed inside mesoporous SiO2/C. A sol-gel process was used for the preparation of this mesoporous composite material (SiO2/C). This mesoporous composite has a pore size of around 13–14 nm, a large surface area (SBET 421 m2·g−1) and large pore volume (0.98 cm3·g−1) as determined by the BET technique. The material compactness was confirmed by SEM images which showing that there is no phase segregation at the magnification applied. The chemical homogeneity of the materials was confirmed by EDX mapping. The SiO2/C/Co3O4 nanomaterial was pressed in desk format to fabricate a working electrode for nonenzymatic amperometric sensing of dopamine at a pH value of 7.0 and at a typical working potential of 0.25 V vs SCE. The detection limit, linear response range and sensitivity are 0.018 μmol L−1, 10–240 μmol L−1, and 80 μA·μmol L−1 cm−2, respectively. The response timé of the electrode is less than 1 s in the presence of 60 μmol L−1 of dopamine. The sensor showed chemically stability, high sensitivity and is not interfered by other electroactive molecules present in blood. The repeatability of this sensor was evaluated as 1.9% (RSD; for n = 10 at a 40 μmol L−1dopamine level. [Figure not available: see fulltext.]