Limiting current density methanol adsorption

Here, is the low-current limiting current density due to the methanol adsorption on the catalyst surface, and is the limiting current due to the methanol transport in the ABL. Note that is proportional to the product of the ACL... 

As was previously mentioned, PtRu alloys exhibit improved performance over pure Pt alloys.117,118 This is primarily a result of the ability of Ru to dissociate H20 for reaction with CO adsorbed on Pt sites.115,116 That CO oxidation on pure Ru is unfavorable indicates that on the bimetallic surface, CO is oxidized only on the Pt sites.119 Thus, CO is oxidized on Pt sites adjacent to Ru sites, where water is activated.120,121 This is known as a bifunctional mechanism. In addition, the presence of Ru atoms reduces the adsorption energy of CO on neighboring Pt atoms, lowering the activation energy of CO oxidation.122 This effect is purely electronic and is less significant than the bifunctional effect of Ru.123 One significant limitation of PtRu is the weak adsorption of methanol on Ru, particularly at room temperature.117,124 The weak adsorption severely hinders methanol decomposition, which is evident in Fig. 7 by the drop in current density for PtRu electrodes with high Ru composition.125... 

For the experimental conditions used (v 0.020 V/s, C = 5 x 10 mol/cm ) with n = 2e /NaCOOH and assuming an 0.5 and D = 10 cm /s yields a theoretical peak current density of 95 mA/cm. The experimental peak current is less than 0.2% of this value, thus formate adsorption rather than diffusion likely limits the reaction rate. It is interesting to note that the reduction of CO2 past the formate stage to form methanol has been recently reported for the Mo... 

The resistance of n-CdSe to photodecomposition varies with solwnt in the following order AN PC > DMF > EtOH MeOH > HzO . Methanol/ [Fe(CN)gf was chosen for subsequent stability tests because of the high rates of electron transfer and its transparence to most of the solar spectrum. The conversion efficiency for the photo-anode at 85 mW/cm (tungsten-halogen illumination) is reported to be 3.5% at a constant current density of 6mA/cm and the fill factor is 0.56 The anode was completely stabilized by the redox couple and no deterioration of the surface or degradation of the photoresponse were observed Specific adsorption at the electrode surface and ion pairs in the bulk solution limit the maximum short-circuit current to 17.5 mA/cm in stirred and 7.5 mA/cm in unstirred solutions Purity of the solvent is essential... 

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