Determining the Active Surface Area for Various Platinum Electrodes
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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.
KeywordsPt electrocatalysts Electrochemically active surface areas (ECAs) Under potential deposition (UPD) Voltammetric stripping Adsorbed hydrogen (H) UPD-Cu CO displacement method CO adsorption
This work was supported by the 100 Talents Program of the Chinese Academy of Science, National Natural Science Foundation of China (NSFC) (project no. 20773116, 21073176) and the 973 Program from the Ministry of Science and Technology of China (project no. 2010CB923302).
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