Determination of the Real Surface Area of Pt Electrodes by Hydrogen Adsorption Using Cyclic Voltammetry

Abstract

It is well known that the electrical current of an electrochemical process is proportional to the real surface area of the electrode. The presence of surface rugosities due to steps, holes, kinks, and terraces can result in an electrode real surface area that is larger than the geometric one. The electrode real surface area can be evaluated by determining the amount of gas that adsorbs onto the electrode surface. This calculation is possible because every adsorbed gas molecule is attached to one metal atom on the electrode surface, forming a gas monolayer. From crystallographic data the surface atom density can be obtained in consideration of a theoretically flat metal surface. These data allow us to determine the real electrode surface area.In this paper we propose a simple experiment to determine the real surface area of a Pt electrode by voltammetry. The hydrogen adsorption on this metal is achieved by applying sufficiently negative potentials to a Pt electrode in contact with an aqueous solution. Each adsorbed hydrogen atom requires the transfer of one electron. Hydrogen gas evolution starts only when the monolayer is completed. Then the cathodic current rapidly rises. The hydrogen monolayer formation charge transference can be calculated by integrating the voltammetric curves. The integration limits are the potentials at which the hydrogen adsorption and evolution start.

Electrochemical Study of Bulk and Monolayer Copper in Alkaline Solution

“…when potential is moved to positive end from negative end), characterized by two prominent current peaks in the said potential range and at still higher potential (0.1 to 0.5 V versus Hg/Hg 2 SO 4 ) platinum surface gets oxidized. [26][27][28] While for the electrode with a Cu monolayer deposited on platinum, no peaks corresponding to hydrogen desorption were observed in the range of −0.68 to −0.3 V during oxidation scan. Indeed, if copper is deposited as complete monolayer, no platinum surface will be available for the hydrogen adsorption and as consequence hydrogen desorption peak will not be observed during oxidation scan.…”

A Study of Dissolved Gas Dynamics in Mixed Stream Electrolyzed Water

“…To determine the roughness factor a CV experiment was performed to measure the hydrogen adsorption wave of the platinum electrode. 20,21 This experiment was performed with a Pine-Wavenow potentiostat, a 3 M Ag/AgCl reference electrode, a 2-mm round flat platinum counter electrode, and a two-sided platinum working electrode with a total measured surface area of 7 cm 2 . The surface roughness was determined to be approximately 6.5.…”

The influence of copper in dealloyed binary platinum–copper electrocatalysts on methanol electroxidation catalytic activities

“…Furthermore, the cyclic voltammogram of Pt 70 Cu 30 /CP depicted in Fig. 7(c) shows a cathodic peak and an anodic peak in the range of 0.4e0.6 V (vs. Ag/AgCl), indicating that the Cu directly bonds to the Pt atoms, i.e., 'Cu under potential deposition (Cu UPD )', and the Cu was later partially removed from the surface [32,40]. In Fig.…”