Influence of temperature on the charging/discharging process of IrO2 coating deposited on p-Si substrate

The influence of temperature on the charging/discharging process of the IrO2 coating deposited on p-Si has been investigated using cyclic voltammetry. The measured apparent activation energy (Ea) depends strongly on the used scan rate in the cyclic voltammetry measurements. In fact at low scan rates (5 mV/s), Ea for the charging/discharging process has a value of about 2.4 kJ/mol; this is related to a slow process due to diffusion of protons within the IrO2 coating. At high scan rates (500 mV/s), Ea reaches a value close to zero. This has been attributed to the double layer capacitance, which is an instantaneous electrostatic process.