Silicon oxycarbide ceramics as promising new materials for electrochemical sensors

Reference	Presenter	Authors (Institution)	Abstract
18-047	Mariana Felix Iastrenski	Iastrenski, M.F.(Universidade Estadual de Londrina); Silva, M.d.(Universidade Estadual de Londrina); Silva, P.R.(Universidade Estadual de Londrina); Parreira, P.S.(Universidade Estadual de Londrina); Dall'Antonia, L.H.(Universidade Estadual de Londrina); Tarley, C.R.(Universidade Estadual de Londrina); Segatelli, M.G.(Universidade Estadual de Londrina);	Silicon oxycarbide (SiOC) ceramics electrical properties have been widely studied for application as Li ion batteries, piezoresistors, supercapacitors and MEMS [1]. Still, these materials exhibit promising chemical features to be used as electrochemical sensors, due to in situ formation of electrically active phases, such as Cfree and SiC. Two structurally distinct polymeric precursors were prepared: DVDH (hydrossilylation reaction between 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, and 2,4,6,8-tetramethylcyclotetrasiloxane) and PMFV (radicalar polimerization of poly[dimethylsiloxane-co-diphenylsiloxane], divinyl terminated). The first one contains silicon cyclic monomers with methyl groups, while the second one is based on a linear polysiloxane with methyl and phenyl groups. SiOC ceramics were obtained by pyrolysis under Ar atmosphere at 1000 and 1500oC. Additionally, pieces of each sample were etched in HF solution 20% (v/v) to remove insulator Si-O-rich domains. Electrochemical behaviour of ceramic-Nujol paste electrodes was analysed by cyclic voltammetry for potassium ferrocyanide and catechol detection. The electrode performances were explained considering the ceramics chemical structure, analysed through techniques such as Raman and FTIR spectroscopies, 29Si-NMR, SEM and XRD. Both polymers originated ceramics adequate as electrodic materials when pyrolysed at 1500oC. PMFV-derived ceramics presented better results for the detection of both analytes, including faster electron transfer kinetics and higher peak currents, compared to vitreous carbon electrode. Also, ceramics treated with HF exhibited enhanced electrochemical response, probably by increase of electroactive area. Seen the commercial and technological importance of SiOC ceramics, this study is relevant since it points out SiOC ceramics as new electrodic materials. This is an unexplored field concerning silicon polymer-derived ceramics. [1] YAN, X.;et al; J. Eur. Ceram. Soc. 35 (2015) 443
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