Electrocatalytic Oxygen Reduction in Carbon-Based Materials

The electrocatalytic reduction of oxygen represents a cornerstone reaction in the pursuit of clean energy technologies, underpinning the performance of fuel cells and metal–air batteries. Carbon-based materials have emerged as versatile platforms for supporting active sites, owing to their high conductivity, tunable porosity and ease of functionalisation. Strategies to enhance activity and durability have centred on the introduction of heteroatoms (such as nitrogen, phosphorus and sulphur) into the carbon lattice, the generation of hierarchical pore structures to facilitate mass transport and the integration of non-precious metal species. Such modifications create favourable electronic environments and abundant catalytic sites, enabling a four-electron reduction pathway that maximises energy efficiency while minimising undesirable by-products. Recent advances have demonstrated that biomass-derived and bio-template methods can yield sustainable, low-cost electrocatalysts with performances approaching those of platinum-based benchmarks. The interconnection between surface chemistry, pore architecture and electron transfer kinetics now guides the rational design of next-generation carbon electrocatalysts for global applications in stationary power, portable devices and transportation.

Research from Nature Portfolio

Seminal work has demonstrated that waste-derived carbon can rival commercial catalysts through intrinsic heteroatom incorporation. One approach transformed human urine into a hierarchical porous carbon doped with nitrogen, sulphur and phosphorus, yielding a durable catalyst with onset and half-wave potentials comparable to platinum on carbon. Another study employed the direct pyrolysis of Shewanella bacteria to produce quaternary-doped carbon frameworks that maintain structural integrity and deliver a dominant four-electron reduction mechanism in alkaline media with excellent methanol tolerance. A further innovation combined haemoglobin and carbon nanotubes to spawn Fe₅C₂ nanoparticle-studded sp² carbon, achieving high current densities and robust performance in both acidic and basic environments. These foundational investigations illustrate the power of biological precursors and in situ heteroatom or metal–carbon interactions to unlock efficient, platinum-free oxygen reduction catalysis.

Electrocatalytic Oxygen Reduction in Carbon-Based Materials publication trend

The graph below shows the total number of articles in electrocatalytic oxygen reduction in carbon-based materials across all publications each year (not limited to Nature Index journals).

Technical terms

Electrocatalyst: A material that accelerates an electrochemical reaction at an electrode surface without being consumed.

Oxygen reduction reaction: The electrochemical process by which O₂ is reduced, typically to water, via two- or four-electron pathways in fuel cells and batteries.

Heteroatom doping: The intentional incorporation of atoms such as N, S or P into a carbon matrix to modify electronic structure and create active sites.

Onset potential: The electrode potential at which a measurable current attributable to the target reaction first appears.

Four-electron pathway: A mechanism of oxygen reduction that transfers four electrons per O₂ molecule, yielding water directly and maximising energy conversion efficiency.

References

1. PGM-Free Biomass-Derived Electrocatalysts for Oxygen Reduction in Energy Conversion Devices: Promising Materials. Electrochemical Energy Reviews (2024).
2. Valorising lignocellulosic biomass to high-performance electrocatalysts via anaerobic digestion pretreatment. Biochar (2024).
3. Heteroatom-doped highly porous carbon from human urine. Scientific Reports (2014).
4. High Performance Heteroatoms Quaternary-doped Carbon Catalysts Derived from Shewanella Bacteria for Oxygen Reduction. Scientific Reports (2015).
5. Hemoglobin-carbon nanotube derived noble-metal-free Fe5C2-based catalyst for highly efficient oxygen reduction reaction. Scientific Reports (2016).