Origin of the current peak of negative scan in the cyclic voltammetry of methanol electro-oxidation on Pt-based electrocatalysts: a revisit to the current ratio criterion

A popular criterion that uses the ratio between the peak currents of the respective positive ( anodic) and negative (cathodic) potential scans, I-f/I-b, in the cyclic voltammetry of methanol electro-oxidation to gauge CO-tolerance and catalytic activity of Pt-based electro-catalysts was revisited and its inadequacy was revealed by an in situ surface enhanced IR study.