A New Type of Scaling Relations to Assess the Accuracy of Computational Predictions of Catalytic Activities Applied to the Oxygen Evolution Reaction

Abstract

Experimentally, it is well known that the overpotentials for the oxygen evolution reaction (OER) on RuO2 and IrO2 are similar and rather low. The question is whether widespread computational electrochemistry models based on adsorption thermodynamics are capable of reproducing such observations. Making use of DFT results of revised Perdew–Burke–Ernzerhof (RPBE) and Perdew–Burke–Ernzerhof (PBE) functionals from six different codes and various types of pseudopotentials, we show that whereas IrO2 is consistently predicted to have low overpotentials, RuO2 is predicted to have large overpotentials. A new methodology based on adsorption‐energy scaling relations shows that the inaccurate prediction for RuO2 stems from its anomalous adsorption energies of oxygen/oxygenates. Including explicit water solvation and using functionals that account for van der Waals interactions such as vdW‐DF, vdW‐DF2 and optPBE‐vdW modifies appropriately the adsorption energies so that both oxides are predicted to be highly active.

Overpotential‐Dependent Volcano Plots to Assess Activity Trends in the Competing Chlorine and Oxygen Evolution Reactions

“…Viswanathan and co‐workers introduced a predictability approach to identify descriptors for electrocatalytic reactions: while IrO 2 (110) is located at the top of the CER volcano, in contrast, RuO 2 (110) is situated at the volcano's leg. In summary, both ab initio studies are not capable to reproduce the trends a CER [RuO 2 (110)]> a CER [IrO 2 (110)] and a OER [RuO 2 (110)]> a OER [IrO 2 (110)] correctly (cf. Table ).…”

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

“…Several ab initio studies based on density functional theory (DFT) were devoted to investigate the surface structure of RuO 2 (110) as function of the applied electrode potential [16][17][18][19][20][21][22][23][24] by using the formalism of the computational hydrogen electrode (CHE) approach, as introduced by Nørskov and co-workers. [30] Under CER conditions, i. e., at U > 1.36 V vs., the RuO 2 (110) surface is completely oxygen terminated: all one-fold coordinatively unsaturated Ru surface atoms (Ru cus ) are capped by ontop oxygen (O ot ) and the neighboring Ru 2f atoms are bridged by undercoordinated surface oxygen (O br ).…”

“…[2,14] The (110) facet as most stable surface termination of the active component RuO 2 is envisioned as an appropriate model system for the investigation of the competing CER and OER on a molecular scale. [15] In the last decade, computational researchers gained in-depth insights into the energetics of adsorbates on the RuO 2 (110) surface under CER/OER conditions [16][17][18][19][20][21][22][23][24] and resolved the reaction mechanism of both mechanistic pathways. [25,26] The concrete knowledge of the kinetics enables a detailed discussion of the pressing selectivity issue for the competing CER and OER.…”

Influence of Van der Waals Interactions on the Solvation Energies of Adsorbates at Pt‐Based Electrocatalysts

“…Numerous recent experimental works show that solvent and/or electrolyte effects change the activity and selectivity of electrocatalysts for important reactions such as oxygen reduction, hydrogen evolution, CO 2 reduction, and CO reduction . In addition, computational works show that solvation and/or cation coadsorption modify the adsorption energies of reaction intermediates, which may not only lead to changes in reaction pathways but also to considerable differences in the calculated activity of electrocatalysts …”