Pitfalls and best practices in measurements of the electrochemical surface area of platinum-based nanostructured electro-catalysts

Platinum-based nanoparticles are the most active and stable catalysts for electrochemical oxygen reduction reaction (ORR). Objective evaluation of the specific activity of Pt-based electro-catalysts requires a rigorous measurement of their electrochemical surface area (ECSA), which provides the link between measured currents and per-site turnover. Most common implementations of existing voltammetry methods for evaluating the ECSA often lead to overrated performance levels for Pt-based electro-catalysts and even inflated relative performance compared to pure Pt. We illustrate these uncertainties by evaluating the ECSA and ORR rates of a Pt-monolayer (ML) electro-catalyst of the form AuxCu100-x@Au-2ML@Pt-ML and comparing these to commercial Pt nanoparticles. We develop and discuss some reasonable practices that could be employed to address these problems in order to assess the activity of Pt-alloy nano-catalysts more rigorously. Our objective was to move us closer toward establishing more uniform and rigorous protocols in measuring and reporting the ORR rates on Pt alloys. (C) 2016 Elsevier Inc. All rights reserved.