Thoughts about Choosing a Proper Counter Electrode

Using a three-electrode configuration cell to evaluate the electrocatalytic performance of materials is the standard way for initial catalyst screening. However, using Pt as the counter electrode has recently raised severe concerns as to the accuracy and reliability of evaluating the hydrogen evolution activity on nonprecious metals, as corrosion of the Pt counter electrode interferes with the results. In this contribution, we use the hydrogen evolution reaction for a case study and demonstrate several basic principles for choosing a proper counter electrode material for different scenarios. The general principle is to minimize the polarization of the counter electrode material by analyzing the reaction on the counter electrode and choosing the best catalyst for it, maximizing the counter electrode to working electrode surface area ratio, and limiting the current magnitude at the working electrode.