Diffiision layer

To investigate the relationship between the interfacial rate constant and the diffiision layer thickness, the protonation reaction rate was measured by the CLM method. The schematic diagram of the CLM apparatus is shown in Figure 10.2. In the CLM method, the thickness of the dodecane phase in the aqueous hydrochloric acid phase can be controlled by the initial volume of each. When the thickness of the dodecane phase was changed from 53 to 132 pm, the observed interfacial diprotonation rate constant decreased from 9.9 x 10 s to 1.5 x 10 s". The experimental results were well reproduced by Equation (1), substituting 3 with the organic phase thickness [10]. 

Charged surface Stem layer Stem plane Plfflie of share Diffiise layer... 

Figure 6.6 Schematic concentration profile at the cathode for pulse plating conditions [6.101] pulsating diffiision layer thickness stationary diffusion layer thickness iJn Nemst diffusion layer thickness.

The total charge of the compact and diffiise layers equals (and is opposite in sign to) the net charge on the elecfiode side. The potential-distance profile aeross tlie double-... 

To electrochemists this expression is clearly related to the diffusion length or Nemst diffusion layer thickness. So the potential step chronoabsorptometry experiment can be regarded as setting up an optical cell with the thickness equal to the Nemst diffusion layer. As time increases, not only does the diffiision layer thickness increase, but so does the amount of light-absorbing product generated in the layer. 

The preparation procedure is briefly described for carbon-based air cathode and Zn gelled anode. The carbon slurry for the gas diffusion layer was prepared with a mixture of 70 wt.% Shawinigan acetylene black (AB50) and 30 wt.% PTFE (Teflon-30 suspension) as a binder. The slurry was coated on a Ni-foam current-collector. The gas diffiision layer was sintered for... 

One very attractive way to circumvent this problem is to apply the catalytic ionic liquid in the form of a supported thin film Such supported thin films provide the whole volume of the ionic catalyst solution close to the fluid-fluid phase boundary, thus within the diffiision layer. The realisation of this concept has been introduced into the literature under the term SILP catalysis. 

Capacitance values. All models except purely diffiise-layer models involve capacitance values. These can be seen as an indication for the distance between respective surface planes (or for the thickness of a layer) ... 

---