The adsorption of carbon monoxide was studied under steady state conditions on smooth rhodium electrodes in 0.5 M H,SO, at room temperature. The coverage with orbon monoxide is equal to saturation coverage between 0.1 and 0.5 V us a hydrogen electrode in the same solution.
Above 0.5 V it decreases to 0 within 0.2 V. The oxidation of chemisorbed carbon monoxide at constant current is accompanied by the formation of the oxygen layer above 0.6 V. A correction for the contribution of the oxygen layer formation to the anodic charge has to be applied in thedetermination of the CO,, coverage even at small current densities.
The coverage with Had was determined as a function of potential at constant coverage with preadsorbed carbon monoxide from anodic charging curves. These curves were taken at a sufficiently small current density so that the equilibrium of the Volmer reaction remained practically established.
The coverage of CO,,, computed from thecharge for the oxidation of CO,, a g reed well with that obtained from thedecrease of the length of the hydrogen branch of the charging curves. The isotherms of hydrogen adsorption are of the Ten&in type at CO, coverages above 0.4. The characteristic parameters of the Temkin isotherm were determined as a function of the coverage with CO,