Caracterização Eletroquímica do compósito CVR/PANI obtidos a partir de CVR de diferentes Porosidades e Temperaturas de Tratamento Térmico

Carbon materials and conducting polymers are known by application in electronic devices. Electrosynthesis start is critical, because it defines morphology and structure of polymeric layers. This work aims evaluate polyaniline (PANI) electrosynthesis on reticulated vitreous carbon (RVC), obtained by using of 9 voltammetric cycles in aniline 0,02 mol L-1 and 1 mol L-1 of H2SO4, in scanning from - 0,25 up to 1,0 V x Ag/AgCl, at 25 mV s-1, using Pt counterelectrode. Using RVC annealed at 1100 and 2100 ºC and with 40 and 70 pores per inch (ppi), the characterization was realized by techniques of cyclic voltammetry (CV) and electrochemical impedance spectroscopy. CV was used to evaluate samples electroactivity. To this aim, it was used 2 cycles from -2,0 up to 1,0 V (vs Ag/AgCl), at sweep rate changing from 10 up to 100 mV s-1 in H2SO4 1,0 mol L-1. EIS was used to know the nature of electrode phenomena, using a frequency interval from 10-2 e 105 Hz, amplitude ±10 mV (RMS), at open circuit potential (OCP) in same solution cell. Data were evaluated by simulation of impedance spectra by NLLS circuit fit analysis. CV of PANI electrosynthesis on RVC revealed that three transitions of oxidation degree, probably related to leucoemeraldine/emeraldine, emeraldine/pernigraniline and pernigraniline/post-oxidation products. RVC 70 ppi annealed at 2100ºC showed more significant signals of current, specially to emeraldine formation, probably because of its conductivity, area and capillary effect greater than others. EIS revealed behavior showed in Figure below, resulting predominantly on [R(QR)(Q[RT])W].At lower frequencies, it is possible to note, at same time effets of two types of diffusion in competition, namely W, related to possible slow electrode reaction of PANI or exposed functional groups of RVC in internal stems, and T, possibly related to saturation of external surface of RVC/PANI electrode. At higher frequencies, another Randles circuit is outlined, indicating reversion on behavior of electrode by negative resistence of solution, but degradation of same blocks the assay and hampers this assert.