Circumventing the Theoretical Scaling Relation Limit for the Oxygen Evolution Reaction

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Transition metal (oxy)hydroxides (TMHs) are promising electrocatalysts for the oxygen evolution reaction (OER) in alkaline media.
• Existing scaling relations limit OER catalyst performance, necessitating new descriptors for optimization.
• Understanding the interplay between dopants and OER mechanisms is crucial for designing efficient catalysts.

Purpose of the Study:

• To investigate the impact of various electron dopants (s, p, and d orbitals) on Ni-based TMHs for OER.
• To identify reliable descriptors that can predict and circumvent the OER scaling relation limitations.
• To determine the energetic favorability of the adsorbate evolution mechanism (AEM) versus the lattice oxygen-mediated mechanism (LOM).

Main Methods:

• Employed first-principles calculations to quantify the effects of dopants on OER overpotential.
• Examined both the adsorbate evolution mechanism (AEM) and the lattice oxygen-mediated mechanism (LOM).
• Analyzed the formation energy of oxygen vacancies (E_V) and its correlation with dopant properties.

Main Results:

• Dopant identity significantly influences the formation energy of oxygen vacancies (E_V) in Ni-based TMHs.
• A clear linear relationship was established between E_V and the free energy difference for oxygen-oxygen coupling.
• A predictive descriptor was identified to distinguish between the energetic preference for LOM over AEM.

Conclusions:

• The formation energy of oxygen vacancies serves as a computationally light descriptor for OER mechanism prediction in doped TMHs.
• These findings provide a pathway to rationally design improved electrocatalysts by circumventing scaling relation limits.
• The identified descriptor aids in selecting optimal dopants for enhancing OER performance via the LOM.