Electrocatalytic Mechanisms in Water Splitting Systems

Water splitting through electrocatalysis converts electrical energy into storable chemical energy by driving the hydrogen evolution reaction at the cathode and the oxygen evolution reaction at the anode. Central to this process is the design of active, stable and cost-effective electrocatalysts that lower the energy barriers for bond formation and cleavage. Mechanistic studies have revealed that reaction pathways often proceed via adsorbed intermediates—such as hydrogen atoms on metal surfaces for hydrogen evolution, or oxy-species for oxygen evolution—with reaction rates governed by adsorption energies, charge-transfer kinetics and mass-transport phenomena. Recent advances in catalyst architecture exploit defect engineering, atomic-level dopants, surface facet control and hybrid supports to optimise active site density and electronic structure. In situ spectroscopic and scattering techniques now permit real-time characterisation of phase transitions and reaction centres, informing the rational design of bifunctional materials capable of driving both half-reactions at low overpotentials. These developments underpin scalable hydrogen production and integration with intermittent renewable power sources.

Research from Nature Portfolio

High-performance bifunctional phosphide catalysts deposited on nickel foam have demonstrated remarkable water-splitting efficiency, achieving 10 mA cm⁻² at just 1.42 V and sustaining 500 mA cm⁻² without decay over extended operation. The combination of iron and nickel phosphides forms interconnected arrays that promote both hydrogen and oxygen evolution.

Operando scattering and absorption studies of nickel–iron and cobalt–iron layered double hydroxides have elucidated an activation process whereby α-phases convert to contracted γ-phases under anodic bias. Density functional theory indicates that oxygen-bridged Fe-M centres follow a Mars–van Krevelen mechanism, stabilising intermediates and accounting for outstanding oxygen-evolution activity.

Lithium-induced conversion of mixed transition metal oxides into ultra-small oxide nanoparticles yields interconnected high-surface-area networks. Nickel–iron oxide nanoparticles produced in this way exhibit bifunctional catalysis, sustaining 10 mA cm⁻² water-splitting current at 1.51 V for over 200 h with negligible degradation.

Electrocatalytic Mechanisms in Water Splitting Systems publication trend

The graph below shows the total number of articles in electrocatalytic mechanisms in water splitting systems 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 by lowering activation energy and facilitating charge transfer.

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

Hydrogen Evolution Reaction (HER): The cathodic half-reaction in water splitting, involving proton reduction to molecular hydrogen.

Oxygen Evolution Reaction (OER): The anodic half-reaction in water splitting, involving the formation of molecular oxygen from water or hydroxide ions.

Turnover Frequency (TOF): The number of reactant molecules converted to product per active site per unit time.

Layered Double Hydroxide (LDH): A class of two-dimensional mixed‐metal hydroxides with interlayer anions, often used as water-splitting electrocatalysts.

References

1. High-performance bifunctional porous non-noble metal phosphide catalyst for overall water splitting. Nature Communications (2018).
2. In-situ structure and catalytic mechanism of NiFe and CoFe layered double hydroxides during oxygen evolution. Nature Communications (2020).
3. Bifunctional non-noble metal oxide nanoparticle electrocatalysts through lithium-induced conversion for overall water splitting. Nature Communications (2015).
4. Mechanosynthesized electroactive materials for sustainable energy and environmental applications: A critical review. Progress in Materials Science (2024).
5. Facet Engineering of Advanced Electrocatalysts Toward Hydrogen/Oxygen Evolution Reactions. Nano-Micro Letters (2023).
6. Three‐dimensional‐printed Ni‐based scaffold design accelerates bubble escape for ampere‐level alkaline hydrogen evolution reaction. Interdisciplinary Materials (2024).