Unraveling the Competition between the Oxygen and Chlorine Evolution Reactions in Seawater Electrolysis: Enhancing Selectivity for Green Hydrogen Production - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue (Article De Synthèse) Electrochimica Acta Année : 2024

Unraveling the Competition between the Oxygen and Chlorine Evolution Reactions in Seawater Electrolysis: Enhancing Selectivity for Green Hydrogen Production

Résumé

Selective oxidation of water without production of chlorine during the electrolysis of seawater is a critical impediment towards obtaining green hydrogen. Indeed, understanding the complex competitive mechanisms of oxygen and chlorine formation at the anode is an analytic challenge. An argument for direct seawater electrolysis is presented with a dissection of the complications that arise at the anode in the presence of seawater ionic constituents such as the chloride ion. Electrolyser system durability and the impact on the current and voltage efficiencies are discussed. Critical challenges at the anode under the acidic conditions of proton exchange membrane water electrolysis interrelate the thermodynamic and kinetic constraints of the oxygen evolution reaction (OER) and the chlorine evolution reaction (CER) to elucidate the heterogenous mechanisms of the OER and the CER and the crucial stability predicament under selective OER electrocatalysis. The selectivity circumstances resolved by Density Functional Theory computations shed insight onto the reaction conditions that select for the preferred OER adsorbate chemisorption on the surface and substantiates the observed overpotentials required for the OER and CER; experimental rotating ring disk electrode analysis further indicate competitive adsorption of OER and CER reactants under an assumed Langmuir isotherm model. Identifying the rate determining step and breaking the scaling relationship of the AEM OER pathway may both improve the stability of the catalyst and achieve lower OER overpotentials. Critical insight is given into designing the heterogeneous electrocatalyst structure with selective facets, additional point defects, and augmented active site density through single atom catalysts. An argument for the utilization of ruthenium for its high natural ubiquity and modulable valence states that can facilitate atomic configurations with optimal active site d-band center energies to promote selective adsorbate binding is presented. Studies of in-situ filtration of the chloride ion under acidic conditions highlight the utility of manganese oxide and silica; the augmentation of the conductivity through manipulation of polaronic interactions; and the design of heterogeneous electrocatalysts with self-healing characteristics demonstrated in select molecular catalysts that may decrease the overpotential of the OER and achieve selectivity. It is with the hope that these design strategies provide insights into future research efforts to uncover an electrocatalytic surface selective for OER evolution under the perilous acidic conditions and reveal an effective solution as serendipitous as the abundancy of a natural resource such as seawater.
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Dates et versions

hal-04632808 , version 1 (02-07-2024)

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Catherine Harvey, Simon Delacroix, Cédric Tard. Unraveling the Competition between the Oxygen and Chlorine Evolution Reactions in Seawater Electrolysis: Enhancing Selectivity for Green Hydrogen Production. Electrochimica Acta, 2024, 497, pp.144534. ⟨10.1016/j.electacta.2024.144534⟩. ⟨hal-04632808⟩
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