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Electrochemical water splitting is a key technology for moving toward a promising energy scenario based on renewable (regenerative) energy resources in that wind and solar energy can be stored and ...

The computational hydrogen electrode (CHE) approach has spurred ab initio investigations in the field of electrocatalysis, since the underlying concept enables to quantify free energy changes, ΔG (...

Extended Tafel plots at various temperatures for an electrocatalyzed reaction and (possibly) its reversed reaction on single-crystalline model electrodes allow for constructing the (essential part of the) free energy surface, in particular the free energies of the transition states (TS). Free energies of the reaction intermediates (RIs) including the chemical nature of active surface sites (S) are hardly accessible to experiment and need therefore to be taken from constrained ab initio thermodynamics calculations. The compact compilation of experimental kinetic data in the form of a free energy diagram enables a critical assessment and validation of theoretical free energy landscapes based on first-principles kinetics. For three prototypical electrocatalyzed reactions, namely the chlorine evolution reaction (CER) and oxygen evolution reaction (OER) over RuO2(110) as well as hydrogen evolution reaction (HER) on Pt(111), we exemplify this universal approach and discuss potential benefits for theoretical mod...

Ultrathin single-crystalline RuO 2(110) films supported on Ru(0001) are employed as model electrodes to extract kinetic information about the industrially important chlorine evolution reaction (CER) in a 5M concentrated NaCl solution under well-defined electrochemical conditions and variable temperatures. A combination of chronoamperometry (CA) and online electrochemical mass spectrometry (OLEMS) experiments provides insight into the selectivity issue: At pH = 0.9, the CER dominates over oxygen evolution, whereas at pH = 3.5, oxygen evolution and other parasitic side reactions contribute mostly to the total current density. From temperature-dependent CA data for pH = 0.9, we determine the apparent free activation energy of the CER over RuO 2(110) to be 0.91 eV, which compares reasonably well with the theoretical value of 0.79 eV derived from first-principles microkinetics. The experimentally determined apparent free activation energy of 0.91 eV is considered as a benchmark for assessing future improved theoretical modeling from first principles.