Electrochemical Oxidation Processes for Hydrogen Production

Electrochemical oxidation processes harness anodic reactions to generate protons and electrons, which combine at a cathode to evolve hydrogen. Traditional water electrolysis is limited by the high overpotential of the oxygen evolution reaction, driving interest in alternative anodic chemistries such as sulphur dioxide oxidation and other depolarised strategies. In the hybrid sulphur cycle, for example, SO₂ is oxidised at a significantly lower cell voltage than water, producing H₂SO₄ at the anode and hydrogen at the cathode. Advances in electrode materials, membrane architectures and reactor design have elevated cell efficiency, while the integration of renewable electricity sources promises a carbon-neutral hydrogen supply. Key developments include the optimisation of catalyst layers to reduce precious-metal loading, the mitigation of membrane crossover and the management of mass transport phenomena within porous electrodes. Collectively, these innovations seek to lower capital and operating costs, enhance system durability and enable modular deployment across industrial, metropolitan and off-grid settings. The global significance of these processes lies in their potential to decarbonise sectors reliant on grey hydrogen and to valorise waste streams such as flue-gas SO₂, thereby coupling pollution control with energy production. Practical applications under development encompass large-scale electrolyser facilities, decentralised units for chemical plants and retrofitting options in existing power-generation infrastructures.

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Electrochemical Oxidation Processes for Hydrogen Production publication trend

The graph below shows the total number of articles in electrochemical oxidation processes for hydrogen production across all publications each year (not limited to Nature Index journals).

Technical terms

Electrochemical oxidation: An anodic reaction in which a species loses electrons, driving proton production and facilitating hydrogen evolution at the cathode.

Sulphur dioxide depolarised electrolysis: A variant of water electrolysis where SO₂ oxidation replaces oxygen evolution, lowering the cell voltage required for hydrogen production.

Overpotential: The additional potential above the thermodynamic value needed to drive an electrochemical reaction at a given rate.

Electrocatalyst loading: The mass of catalyst per electrode area, a critical factor in cost, activity and durability of electrochemical cells.

Mass transport limitations: Constraints on reaction rates arising from the movement of reactants and products to and from the electrode surface.

Membrane–electrode assembly (MEA): The integrated unit comprising the ion-conducting membrane, catalyst layers and gas diffusion media in an electrolyser cell.

References

1. Electrospray Deposition of Catalyst Layers with Ultralow Pt Loading for Cost-Effective H2 Production by SO2 Electrolysis. ACS Applied Energy Materials (2022).
2. Mass Transport Influence in the SO2 Oxidation Reaction on Au Electrodes. ChemElectroChem (2023).
3. Adjusting the operating boundaries for the mitigation of SO2 crossover in sulphur depolarized electrolysers. Journal of Power Sources (2024).