Comparison of the Conventional Volcano Analysis with a Unifying Approach: Material Screening Based on a Combination of Experiment and Theory

Material screening in electrocatalysis has been spurred by the concept of volcano plots, which rely on analyzing binding energies at zero overpotential. Recently, a unifying material-screening approach was introduced by the author: the combination of first-principles calculations with a single experimental input parameter, that is, the threshold overpotential, at which the experimental Tafel slope exceeds 59 mV/dec in the respective class of materials, results in an ESSI-descriptor activity map. Therein, besides the analysis of binding energies, also the applied overpotential, decisive reaction intermediate, rate-determining reaction step, and electrochemical-step symmetry index (ESSI) are accounted for. On the example of the oxygen evolution reaction over RuO2(110) surfaces, the two different frameworks are compared: while the conventional volcano method relies on a rough screening of the parameter space, as possibly promising surface configurations could be overlooked, the concept of ESSI-descriptor activity maps accounts for a more thorough sorting of electrode materials.