Does the breaking of adsorption-energy scaling relations guarantee enhanced electrocatalysis?

Abstract

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Controlling Stability and Selectivity in the Competing Chlorine and Oxygen Evolution Reaction over Transition Metal Oxide Electrodes

“…I would like to mention that the free energy distance between the limiting OOH and OCl adsorbate can also be enhanced by breaking the linear scaling relations of the two limiting surface phases. [90][91][92][93] However, this is difficult to achieve in the DFT calculations and rarely observed in experiments so that a discussion of breaking the linear scaling functions between the OOH and OCl adsorbate is not in the scope of the present manuscript.…”

Universality in Oxygen Evolution Electrocatalysis: High‐Throughput Screening and a Priori Determination of the Rate‐Determining Reaction Step

“…[14] Lately, advanced material-screening frameworks that combine experimental and theoretical data or take the kinetics and/ or applied overpotential into consideration have been reported in the literature. [15][16][17][18] Herein, the author made the first step to derive a holistic approach by connecting different perspectives in the field of oxygen evolution electrocatalysis, [18] such as binding energies, [6] kinetics (rate-determining reaction step), [19,20] applied overpotential, [14,21] and catalytic symmetry, that is, the electrochemical-step symmetry index (ESSI), [22,23] as a measure for the activity. As a result, ESSI-descriptor activity maps are derived, which allow discriminating electrode materials into potentially interesting (active) or inactive catalysts.…”

“…The ESSI-ΔG 2 activity map in Figure 1 depicts the general idea of this concept: the ESSI, which corresponds to the symmetry of the four free-energy changes οn a potential scale, ΔG j /e (j = 1, 2, 3, 4), with respect to the equilibrium potential of the reaction, U 0 OER = 1.23 V vs. RHE, was introduced by Govindajaran et al [22,23] as an improved thermodynamic measure for the activity compared to the commonly used framework of the thermodynamic overpotential (cf. SI, Section 3).…”

“…In contrast, materials with large ESSI-values are not suitable for the OER due to their inherent thermodynamic restraints. [18,22,23] By using a training set consisting of transition-metal oxides, [30] RuO 2 -based materials, [31] porphyrins, [32] perovskites, [33] functionalized graphitic materials, [34] and metal oxides [33] it has been shown that ESSI = 0.45 V is a suitable threshold to distinguish between active and inactive OER catalysts. [18,24] Therefore, only materials with ESSI < 0.45 V are further processed, whereas electrocatalysts comprising ESSI > 0.45 V can be discarded due to the strong asymmetry of the free-energy changes.…”

Modeling the Catalyst Activation Step in a Metal–Ligand Radical Mechanism Based Water Oxidation System

“…A number of previous studies have proposed that the origin of this substantial overpotential is due to the non-ideal scaling relationship between *OH and *OOH, two intermediates of the OER [3][4][5]. While the ideal energetic separation between these intermediates should be 2.46 eV, it is found to be ∼3.2 eV for most metal oxides and a number of molecular catalysts [3,6]. Therefore significant efforts have been directed in the past few decades towards identifying highly efficient OER catalysts [2,7].…”