Various methods, i.e., the adsorption/stripping of adsorbed probe species, such as hydrogen (H), copper (Cu), and carbon monoxide (CO), oxygen and hydroxide (O/ OH), potentiostatic CO/H displacement as well as double layer capacitance are exploited to evaluate the electrochemically active surface areas (ECAs) of platinum (Pt) foils, chemically deposited Pt thin film, and carbon-supported Pt nanoparticle electrodes. For the relatively smooth Pt electrodes (roughness factor < 3), the measurements from the stripping of H, Cu, and CO adlayers and CO/H displacement at 0.08 V (vs. RHE) give similar ECAs. With the increase of the surface roughness, it was found that the ECAs deduced from the different methods have the order of CO/H displacement less than the stripping of under potential deposition (UPD) Cu monolayer less than the stripping of the UPD-H adlayer. Possible origins for the discrepancies as well as the applicability of all the abovementioned methods for determining ECAs of various Pt electrodes are discussed, and the UPD-Cu method is found to be the most appropriate technique for the determination of ECAs of Pt electrodes with high roughness factors or composed of nanoparticles with high dispersion.

Methanol (MeOH) oxidation reaction (MOR) at Pt electrodes under potentiostatic conditions has been investigated by electrochemical in situ FTIR spectroscopy (FTIRS) in attenuated-total-reflection configuration under controlled flow conditions in 0.1 M HClO(4) with 2 M MeOH, where the mass transport effects are largely eliminated using a flow cell. Our results reveal that (i) at constant potentials, the methanol dehydrogenation rate decreases while the CO(ad) oxidation rate increases with the accumulation of CO(ad) until the maximum CO(ad) coverage (ca. 0.5 ML i.e., the steady state) is reached; (ii) at fixed CO(ad) coverage, the rates for MeOH decomposition to CO(ad) and CO(ad) oxidation increases with potential from 0.3 to 0.7 V (vs. RHE), with Tafel slopes for MeOH dehydrogenation of ca. 440 ± 30 mV/dec, which is independent of CO(ad) coverage; (iii) the current efficiency of the CO pathway in MOR at 0.6 and 0.7 V is below 20% and it decreases toward higher potentials. The mechanisms as well as the potential induced change in the kinetics of different pathways involved in MOR are briefly discussed.

The effects of temperature, CO(ad) surface coverage, and electrode potential on the desorption of CO(ad) from Pt film electrodes in 0.5 M H(2)SO(4) have been investigated by electrochemical in situ FTIR spectroscopy under an attenuated-total-reflection configuration (EC-FTIRS). The major findings are: (i) When theta(rel)>or= 0.53 (theta(CO) is the relative CO(ad) coverage), CO(ad) desorption takes place at T > 40 degrees C (as confirmed by the decrease in both of the C-O(L) stretching frequency as well as the CO(ad) stripping charge), and when theta(rel) is below 0.39, no CO(ad) desorption is observed at temperatures up to 70 degrees C; (ii) A slight increase in CO(ad) desorption rate with electrode potential from 0.1 to 0.3 V and fast adsorption/desorption equilibrium in solution saturated with CO are observed; (iii) From the temperature-dependent changes in CO(ad) surface coverage, the activation energies for CO(ad) desorption are determined to be in the range of 104 and 117 kJ mol(-1), which increases with decreasing CO(ad) coverage.