Marking Electrocatalysts on the “Volcanic Belt” of Hydrogen Electrode Reactions

The Sabatier volcano is an important theoretical tool for directing electrocatalysis studies. However, it has recently become increasingly clear that the peak position of the volcano is significantly impacted by the electrode potential applied. It is therefore more appropriate to represent the property of electrocatalysts by a two-dimensional volcano, namely, a “volcanic belt”, which includes an extra dimension of electrode potential rather than a single volcano plot. While the potential-dependent volcano plot is being actively discussed, it remains unclear how to represent a catalyst in the volcanic belt, which is of critical importance for expressing the impact of the electrode potential on catalysts. Our work here represents an important step in this field. We use the hydrogen electrode reaction as a case study and show that an electrocatalyst (or an electrocatalytic site) can be denoted simply by a straight line named “simplified catalyst trace (sCT)”. The adsorption Gibbs energy and lateral interaction can be well reflected in such sCT. We take hydrogen evolution/oxidation on Rh2P and Rh as examples to show the application of sCT on the volcanic belt.