Redox Characterization of the Ferri/Ferrocyanide System on the P-type Silicon Paste Electrode for Biosensor Application

Silica-based materials generate the highly reactive silanol against metallic trace elements in contact with aqueous solutions. Their use in electroanalysis allows the creation of electrochemical sensors for the regular control of matrices. Silicon, a material derived from silica, is introduced into electroanalysis as an electrode material. This work deals with the study of the semiconductor/aqueous electrolyte junction in cyclic voltammetry. The study of the electrochemical behavior of ferri /ferrocyanide with the silicon paste electrode gives a frayed cyclic voltammogram whose anodic and cathodic redox peaks appear respectively at 0,38 V and 0,08 V vs Ag/AgCl/KClsat. The intensity of the anodic and cathodic peak current are respectively equal to 1,5 µA and – 0,5 µA. This low value shows that the PP junction is weakly conductive. The diffusion coefficients of ferri and ferrocyanide species are 1,15.10-4 and 6,68.10-5cm2.s-1.The oxidizing species diffuses faster than the reduced species. The voltammogram is influenced by the surface energy states of the semiconductor electrode. Its linearization makes it possible to obtain the slope of the curve which is the value of the differential capacitance of the state of surface Ces = 1,45.10 -9 F. The p-doped silicon paste electrode is weakly active in electrochemistry in the dark.