Electrocatalytic Oxygen Evolution Mechanisms and Materials

The oxygen evolution reaction (OER) is a four-electron process central to water splitting and rechargeable metal-air batteries. Mechanistically, OER proceeds via adsorbate evolution pathways on active sites, with key steps including hydroxide adsorption, deprotonation and O–O bond formation. In some materials, lattice oxygen can also participate, lowering energy barriers through reversible oxygen vacancy formation. Catalysts are designed to optimise binding energies of intermediates (OH*, O* and OOH*) while maintaining electrical conductivity, structural stability and large surface area. Transition metal oxides, particularly spinel (AB₂O₄) and perovskite (ABO₃) frameworks, remain front-runners owing to their tunable electronic structures and abundant active sites. Incorporation of heteroatoms, creation of oxygen vacancies and construction of hierarchical nanostructures further enhance intrinsic activity and mass transport. Composite architectures using carbon-based supports (graphene, nanotubes, foam) bolster conductivity and dispersibility of active phases. The global drive towards green hydrogen intensifies efforts to replace precious-metal benchmarks with earth-abundant materials that deliver low overpotential, small Tafel slopes, high turnover frequencies and long-term stability under alkaline or neutral conditions. Synergistic design of mixed-metal oxides, precise dopant control and in situ characterisation are advancing mechanistic understanding and accelerating the deployment of scalable, cost-effective OER electrocatalysts.

Research from Nature Portfolio

Recent studies report spinel-structured nickel cobaltite integrated with nitrogen-doped carbon to produce hybrid electrodes exhibiting enhanced conductivity and optimised active-site exposure. Morphological analyses reveal nanoscale interfaces between NiCo₂O₄ domains and doped carbon layers, which promote rapid charge transfer and stabilise high-valent Co⁴⁺ and Ni³⁺ species during OER. Another foundational work demonstrated that homogeneously coated NiₓCo₃₋ₓO₄ nanocrystals on pristine carbon nanotubes deliver bifunctional activity for both oxygen evolution and reduction, achieving low overpotentials and durable operation by preserving the intrinsic conductivity of the support. Seminal research on Au-decorated NiCo₂O₄ on three-dimensional graphene-like scaffolds illustrated that introduction of a noble-metal electron acceptor can stabilise catalytically active cations and boost oxygen turnover frequencies, setting benchmarks for non-precious metal systems.

Electrocatalytic Oxygen Evolution Mechanisms and Materials publication trend

The graph below shows the total number of articles in electrocatalytic oxygen evolution mechanisms and materials across all publications each year (not limited to Nature Index journals).

Technical terms

Overpotential: The extra potential beyond the thermodynamic requirement needed to drive an electrochemical reaction at a specified rate.

Tafel slope: A parameter describing the change in overpotential with current density, indicative of reaction kinetics and rate-determining steps.

Spinel structure: A crystalline framework of the form AB₂O₄, where A and B are metal cations occupying distinct lattice sites, enabling electronic and structural tuning.

Turnover frequency (TOF): The number of reactant molecules converted per active site per unit time, reflecting intrinsic catalytic activity.

Active site: A specific atomic or molecular configuration on a catalyst surface where reactants are adsorbed and transformations occur.

Oxygen vacancy: A missing oxygen atom in a metal oxide lattice, which can enhance electronic conductivity and facilitate lattice oxygen participation.

Current density: The electric current per unit area of electrode surface, used to benchmark electrocatalyst performance.

References

1. Enhancing the physicochemical properties of nickel cobaltite catalyst for oxygen evolution reaction in anion exchange membrane water electrolyzers. Materials for Renewable and Sustainable Energy (2024).
2. Au-NiCo2O4 supported on three-dimensional hierarchical porous graphene-like material for highly effective oxygen evolution reaction. Scientific Reports (2016).
3. Decorating unoxidized-carbon nanotubes with homogeneous Ni-Co spinel nanocrystals show superior performance for oxygen evolution/reduction reactions. Scientific Reports (2017).
4. A Comparative Study of NiCo2O4, NiO, and Co3O4 Electrocatalysts Synthesized by a Facile Spray Pyrolysis For Electrochemical Water Oxidation. Advanced Materials Interfaces (2023).
5. Combined effect of nitrogen-doped carbon and NiCo2O4 for electrochemical water splitting. Scientific Reports (2024).
6. L-lysine and surfactant-assisted synthesis of NiCo bimetal oxides for electrochemical water splitting. iScience (2024).