Improved electrochemical surface area measurement of platinum using a potential holding strategy

• A potential holding method was developed for accurate ECSA determination of Pt. • HER and multilayer effects were minimized by time-controlled potential application. • Consistent roughness factors were obtained using both H-adsorption and Cu-UPD. • This method offers a reliable alternative to conventional cyclic voltammetry for ECSA measurement. As research in energy and environment field expands with the advancements in nanotechnology, the importance of electrochemical characterization of materials has grown significantly. Generally, the electrochemical properties are normalized with electrochemical surface area (ECSA) of the electrodes to assess the intrinsic performance of the electrode materials. Therefore, the estimation of the ECSA value of the materials is crucial for interpreting their intrinsic properties. The most widely used method for ECSA determination involves cyclic voltammetry (CV) based on hydrogen adsorption/desorption. Although this technique is simple and utilizes an adsorbate with a smaller size than other methods, challenges remain in confirming whether a proper hydrogen monolayer has been formed. In this study, we introduce the first systematic investigation of a potential holding method as an alternative to conventional CV-based techniques for ECSA determination on Pt electrodes. By precisely controlling the holding potential (H ptl ) and time (H time ), we achieved reliable monolayer adsorption while minimizing hydrogen evolution reaction (HER) and the accumulation of surface-adsorbed hydrogen beyond monolayer coverage (i.e., multilayer effects). To validate this approach, copper underpotential deposition (Cu-UPD) was also performed using the same potential holding strategy. Both methods yielded consistent roughness factors: 1.93 for hydrogen adsorption and 1.97 for Cu-UPD. These results confirm the reliability of the potential holding method and establish it as a standardized alternative to conventional cyclic scanning techniques in ECSA measurements for electrocatalyst characterization.