Material carbono ceramico condutor SiO2/ZrO2/C-grafite : sintese, caracterização e aplicações / SiO2/ZrO2/C-graphite conducting carbon ceramic material : synthesi characterization and application




SiO2/ZrO2/C-graphite was prepared by the sol-gel method in two compositions: (A) SZC30 (SiO2 = 50 %, ZrO2 = 20 %, C = 30 %) e (B) SZC20 (SiO2 = 60 %, ZrO2 = 20 %, C = 20 %) in % m/m, characterized and used to prepare electrodes. The carbon ceramic material was thermally treated at 400, 600, 800 and 1000 °C in nitrogen atmosphere, and it was observed that it presents high thermal stability and the crystallization of ZrO2 occurred at 1000 °C in tetragonal phase, while SiO2 remained amorphous. The specific surface area of SZC20 and SZC30 the carbon ceramic materials was, respectively, 45 and 12 mg, as prepared. For materials treated at temperatures higher than 600 °C, due to the collapse of the porous, specific surface area of the materials decrease to 3 and 4 mg. High resolution transmission electron microscopy micrographs showed that the graphite nanoparticles are well dispersed inside SiO2/ZrO2 matrix, and these nanoparticles are responsible for the high electrical conductivity of pressed disks of carbon ceramic materials, 4 and 18 S cm, respectively. The SZC30 material was used to prepare electrodes and they were modified with copper hexacyanoferrate(II) (CuHCF) and flavin adenine dinucleotide (FAD). The thickness of the CuHCF film was estimated as 101 nm, presenting good chemical stability and low charge transfer resistance. FAD modified SZC30 carbon ceramic electrode was efficient for electrocatalytic reduction of bromate and iodate ions, in aqueous solution. The electroreduction of both ions occurred at a peak potential of - 0,41 V vs. saturated calomel electrode. The cronoamperometry experiments showed that FAD modified SZC30 carbon ceramic electrode can be used as an amperometric sensor for bromate and iodate, presenting detection limit of 2,3 and 1,5 mmol L, respectively.


carbon ceramic carbono ceramico sio2/zro2/c-grafite sensores eletroquimicos sol-gel sio2/zro2/c-graphite electrochemical sensors sol-gel

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