Thin film of copper hexacyanoferrate dispersed on the surface of a conducting carbon ceramic material, SiO2/ZrO2/C-graphite: characteristics and electrochemical studies

Abstract

O material SiO 2 /ZrO 2 /C-graphite (SZC) foi preparado pelo método sol-gel apresentando duas composições, designadas por: (a) SZC30 (SiO 2 = 50%, ZrO 2 = 20%, C= 30%) e (b) SZC20 (SiO 2 =60%, ZrO 2 = 20%, C= 20%) em % m. A estrutura do material foi investigada por difração de raios X (XRD), microscopia eletrônica de transmissão de alta resolução (HR-TEM) e espectroscopia de fotoelétrons excitados por raios X (XPS). A condutividade elétrica dos discos prensados destes materiais foi 4 e 18 S cm -1 para SZC20 e SZC30, e a área superficial específica (determinado pelo método BET) dos compósitos carbono cerâmico foi 45 e 12 m 2 g -1 , respectivamente. Um filme fino de hexacianoferrato(II) de cobre foi formado in situ na superfície do material contendo 30 % (em massa) de grafite (SZC30). A espessura do filme foi estimada como sendo 110 nm. O potencial médio para o processo redox foi dependente da concentração de eletrólito suporte na faixa de 0,1 a 1,0 mol L -1 de KCl e a resistência de transferência de carga, determinada por espectroscopia de impedância eletroquímica (EIS), foi de 23,8 ohm cm 2 .SiO 2 /ZrO 2 /C-graphite materials (SZC) were prepared by the sol-gel method presenting two compositions and designated as: (a) SZC30 (SiO 2 = 50%, ZrO 2 = 20%, C= 30%) and (b) SZC20 (SiO 2 =60%, ZrO 2 = 20%, C= 20%) in wt.%. The material structure was investigated by X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). The electrical conductivities obtained for the pressed disks of these materials were 4 and 18 S cm -1 for SZC20 and SZC30, and the specific surface areas (determined by the BET method) of the carbon ceramic composites were 45 and 12 m 2 g -1 , respectively. A copper hexacyanoferrate thin film was grown in situ on the material surface containing 30 wt.% C (SZC30). The thickness of the film was estimated as 110 nm. The midpoint potential for the redox process was dependent on the KCl supporting electrolyte concentrations in the range between 0.1 and 1.0 mol L -1 and the charge transfer resistance determined by electrochemical impedance spectroscopy experiment was 23.8 ohm cm 2 .Keywords: silica-zirconia-graphite, carbon ceramic material, conducting ceramic material, copper hexacyanoferrate film IntroductionTransition metal hexacyanoferrates have been the subject of widespread interest because of their electrocatalytic, electrochromic, ion exchange, ion sensing and photomagnetic properties, as recently pointed out in a review where electrosynthesis, in situ characterization and technological applications of Prussian Blue analogues are emphasized. 1 These metal hexacyanoferrate compounds are usually prepared by chemical and electrochemical methods. To support films of these materials on solid surfaces, when necessary, inert substrates such as glassy carbon, graphite, platinum or gold have been used. [2][3][4][5][6][7] Porous substrates such as SiO 2 coated with thin films of SnO 2 , TiO 2 and ZrO 2 have also been used as substrates to adher...

Material carbono ceramico condutor SiO2/ZrO2/C-grafite

“…Materiais com características semelhantes ao descrito no esquema 2, designados como materiais carbono cerâmico, têm sido preparados pelo método sol-gel [16][17][18] e seu uso como substrato para suportar espécies eletroativas tem atraído grande interesse nos últimos anos [19][20][21][22][23][24][25][26][27].…”