This work aimed to determine the voltammetric charges at the electrode / electrolytic solution interface of the IrO2, PtOx and IrO2-PtOx electrodes. The scanning electron microscope characterization (SEM) showed the presence of the IrO2 and PtOx coating deposited on titanium supports. Also, this characterization revealed that the surface of the prepared electrodes is porous and rough. The cyclic voltammetry measurements allowed to show that the voltammetric charge is high at low scan rates. This result is due to the accessibility of the internal and external surfaces of prepared electrodes by electrolytic solution. In contrast, for the high scan rates, only the external (geometric) surface is in touch with the electrolyte. The voltammetric charge decreases when the pH of electrolyte increases. Regardless of the electrolytic solution the voltammetric charges increases in the order: PtOx < IrO2 < PtOx-IrO2. In the absence of free protons (KClO4 and KOH medium), the electrolyte diffuses inside the pores of the deposit regardless of its composition. Thus, all our electrodes have a large number of internal active sites. This study revealed that the processes which take place at the electrode / electrolyte interface are complex. These processes depend on several factors including the composition of the deposit, the proton concentration, etc. The linear correlations between the total voltammetric charge (q*tot) and the total capacitance (Ctot) show that they can be used to represent the extension of the electrochemically active surface.

The main objective of this study is to prepare activated carbon based on corn cobs with excellent adsorbent properties. To do this, a plan of experience was applied to 16 coals prepared with KOH and H3PO4 at different temperatures and concentrations. The plan of experience revealed that KOH, 1M carbon with a specific surface of 546.77 m2/g is the best. Experience has shown that H3PO4, 2M has a specific surface of 613.14 m2/g. The carbon activated by H3PO4 was characterized by determining the iodine number, the ash content, the surface functions, the pHzc and scanning electron microscopy (SEM). The results showed that activated carbon has a high iodine number (674.506 mg/g) and low ash content (6%). In addition, the carbon is acidic and has a porous surface.