Nonenzymatic amperometric dopamine sensor based on a carbon ceramic electrode of type SiO2/C modified with Co3O4 nanoparticles

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 time 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−1 dopamine level.