Hard Lewis acid induced chloride repulsion for durable neutral seawater electrolysis

Abstract

The development of efficient and stable catalysts for the neutral seawater oxygen evolution reaction (OER) is essential for sustainable hydrogen production; however, the competitive chlorine evolution reaction (CER) poses a critical challenge. Herein, nanosheet-like RuO₂@Nb₂O₅ catalysts are constructed and applied to repel Cl⁻ in seawater based on the Lewis acid-base theory. Experiments combined with density functional calculations reveal that Nb₂O₅ as a hard Lewis acid is able to promote the decomposition of H₂O molecules, and the in-situ generated OH⁻ layer significantly reduces Cl⁻ interaction. Notably, Nb₂O₅ also modulates the electronic structure of RuO₂, weakening Cl⁻ adsorption and shifting the OER pathway from the lattice oxygen mechanism to the more stable adsorbate evolution mechanism. After electrolysis for the same duration, the concentration of ClO⁻ in the electrolyte of RuO₂@Nb₂O₅ is approximately one magnitude lower than that of commercial RuO₂. The obtained RuO₂@Nb₂O₅ shows impressive OER activity in neutral seawater (pH ≈ 7.8) and displays considerable durability for up to 100 h.