Bifunctional Electrocatalysis in Oxygen Reaction Systems

Bifunctional electrocatalysis in oxygen reaction systems addresses the dual challenge of accelerating both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) within a single material framework. Such catalysts play a pivotal role in reversible electrochemical energy devices, including rechargeable metal–air batteries, unitised regenerative fuel cells and integrated water‐splitting systems. The fundamental requirement is to achieve low overpotentials and robust stability under alternating reductive and oxidative regimes, often in alkaline or neutral electrolytes. Progress has centred on designing transition-metal oxides, carbon-supported metal nanoparticles, and heteroatom-doped hybrid architectures, exploiting electronic structure tuning, defect engineering and strong catalyst–support interactions. Key performance metrics encompass onset potential, half-wave potential, Tafel slope and long-term durability under cyclic operation. The global imperative to replace noble metals has driven exploration of cobalt, manganese and nickel centres embedded in spinel lattices, metal–organic framework derivatives and nitrogen-rich carbon matrices, all tailored to deliver balanced ORR and OER activity for sustainable energy conversion.

Research from Nature Portfolio

Recent studies have demonstrated that cobalt–manganese spinel nanoparticles with precisely controlled phase and composition can deliver near-benchmark ORR activity in alkaline media while retaining exceptional OER durability. A mild solution-based synthesis yields ultrasmall Co_xMn_3−xO₄ crystallites strongly coupled to carbon supports, exhibiting onset potentials and current densities approaching those of Pt/C and IrO₂ benchmarks. Investigations into nitrogen-doped graphene hollow microspheres anchored with CoO nanoparticles have revealed that quaternary nitrogen sites promote CoO nucleation and yield bifunctional performance surpassing commercial platinum-based catalysts for ORR and matching state-of-the-art OER catalysts in activity and stability. Furthermore, metal–organic framework precursors have been carbonised to produce cobalt-embedded N-doped nanoporous carbons, where optimisation of pyrolysis temperature controls cobalt dispersion and graphitic character, achieving onset potentials close to 0.92 V for ORR and low overpotentials near 1.43 V for OER, together with excellent cyclic endurance.

Bifunctional Electrocatalysis in Oxygen Reaction Systems publication trend

The graph below shows the total number of articles in bifunctional electrocatalysis in oxygen reaction systems across all publications each year (not limited to Nature Index journals).

Technical terms

Bifunctional electrocatalyst: a material capable of efficiently catalysing both the oxygen reduction reaction and the oxygen evolution reaction, enabling reversible operation in electrochemical devices.

Oxygen reduction reaction (ORR): the electrochemical process in which molecular oxygen is reduced, typically at the cathode of fuel cells or metal–air batteries.

Oxygen evolution reaction (OER): the electrochemical process by which water is oxidised to produce oxygen, commonly occurring at the anode during water splitting.

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

Spinel structure: a crystallographic arrangement of metal oxides with general formula AB₂O₄, valued for tunable electronic properties and catalytic activity.

References

1. Phase and composition controllable synthesis of cobalt manganese spinel nanoparticles towards efficient oxygen electrocatalysis. Nature Communications (2015).
2. Interaction Induced High Catalytic Activities of CoO Nanoparticles Grown on Nitrogen-Doped Hollow Graphene Microspheres for Oxygen Reduction and Evolution Reactions. Scientific Reports (2016).
3. Metal-organic-frameworks derived cobalt embedded in various carbon structures as bifunctional electrocatalysts for oxygen reduction and evolution reactions. Scientific Reports (2017).
4. Tunable Bifunctional Activity of MnxCo3−xO4 Nanocrystals Decorated on Carbon Nanotubes for Oxygen Electrocatalysis. ChemSusChem (2018).
5. Cerium-Doped CoMn2O4 Spinels as Highly Efficient Bifunctional Electrocatalysts for ORR/OER Reactions. Catalysts (2022).