Electrocatalytic Mechanisms in Metal-Free Carbon Systems

Metal-free carbon materials have emerged as versatile electrocatalysts for key reactions such as the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Their performance derives from tailored electronic structures, abundant surface defects and heteroatom dopants that create active sites capable of adsorbing and transforming reaction intermediates. Unlike metal‐based catalysts, carbon‐based systems offer tunable π-conjugation, high conductivity and chemical robustness. Mechanistic studies reveal that charge redistribution around dopants or functional groups can optimise adsorption energies of species such as *OH, *O and *OOH, thereby lowering energy barriers. Operando spectroscopic techniques have identified reactive intermediates including superoxide and hydroperoxo species, confirming multi‐step pathways driven by sequential electron and proton transfers. These insights guide the rational design of polymeric hydrogels, covalent organic frameworks and doped graphene to achieve low overpotentials, high current densities and long‐term stability across wide pH ranges. The integration of theoretical modelling and advanced characterisation underpins progress towards sustainable, scalable carbon‐based electrocatalysts for energy conversion and storage.

Research from Nature Portfolio

A mesostructured polymeric hydrogel derived from polyacrylate displays OER activity comparable to benchmark iridium dioxide in alkaline media, with exceptional durability and adaptability across pH values. Electrokinetic analysis and density functional theory demonstrate that positively charged carbon atoms in carboxylate units serve as intrinsic OER active sites. Operando spectroscopy captures the formation of a superoxide intermediate on the hydrogel backbone, revealing an adsorbate evolution mechanism that underlies its high performance and offering a new class of metal‐free OER electrocatalysts.

Electrocatalytic Mechanisms in Metal-Free Carbon Systems publication trend

The graph below shows the total number of articles in electrocatalytic mechanisms in metal-free carbon systems across all publications each year (not limited to Nature Index journals).

Technical terms

Electrocatalysis: Acceleration of electrochemical reactions at an electrode surface by a catalyst.

Oxygen evolution reaction (OER): Anodic half‐reaction in water splitting that produces O₂ from water.

Oxygen reduction reaction (ORR): Cathodic half‐reaction where O₂ is reduced to water or hydroxide ions.

Covalent organic framework (COF): Crystalline porous polymer formed by strong covalent bonds between light elements.

Overpotential: Extra potential above the thermodynamic requirement needed to drive an electrochemical reaction at a desired rate.

P-orbital: Atomic orbital with dumbbell shape that influences electron distribution and bonding in π-conjugated systems.

References

1. A polymeric hydrogel electrocatalyst for direct water oxidation. Nature Communications (2023).
2. Engineering p‐Orbital States via Molecular Modules in All‐Organic Electrocatalysts toward Direct Water Oxidation. Advanced Science (2024).
3. Active sites engineering leads to exceptional ORR and OER bifunctionality in P,N Co-doped graphene frameworks. Energy & Environmental Science (2017).
4. B, N Codoped and Defect‐Rich Nanocarbon Material as a Metal‐Free Bifunctional Electrocatalyst for Oxygen Reduction and Evolution Reactions. Advanced Science (2018).