[Ta6O19]8−-mediated interfacial OH− supply for efficient seawater electrolysis

Seawater electrolysis is promising yet challenging, as the rapid multi-step deprotonation process of oxygen evolution reaction (OER), along with the Ca 2+ , Mg 2+ ions, would deplete the accessible OH − ions near the catalyst-electrolyte interface. Herein, we present the hexatantalate [Ta 6 O 19 ] 8− ({Ta 6 }), a robust H-bond acceptor (HA) to customize the interfacial H-bonds and charge transfer of the layered metal organic framework (MOF) electrocatalyst, for efficiency alkaline seawater OER. Experimental findings reveal that the {Ta 6 } cluster reconstructs the H-bond networks both in the MOF interlayers and at the catalyst-electrolyte interface, liberating more free OH − to penetrate the Helmholtz plane and adsorb onto the catalyst surface. The increased accessible OH − deepens the partial reconstruction degree of the MOF into active components. Besides, the {Ta 6 } cluster modulates the electronic configuration of Ni active sites in the MOF framework, enabling the synthesized R-MOF-Ta 6 /NF electrocatalyst to achieve a low overpotential of 235 mV at a current density of 10 mA cm −2 . Moreover, the anion exchange membrane (AEM) electrolyzer utilizing the R-MOF-Ta 6 /NF anode catalyst could operate 195 h at industrial current density (≥200 mA cm −2 ). This study presents a neoteric strategy to enhance the performance of layered catalysts for seawater OER. The hexatantalate [Ta 6 O 19 ] 8− ({Ta 6 }) serves as a robust H-bond acceptor (HA), effectively disrupting the H-bonds in the layers of the Ni-based MOF and at the catalyst-electrolyte interface. Besides, the electron configuration of the Ni active sites is modulated by the d orbitals of {Ta 6 }, leading to a favorable OER catalytic performance in alkaline seawater. • [Ta 6 O 19 ] 8− reconstructs the H-bond networks at the catalyst-electrolyte interface. • More free OH − penetrate the inner Helmholtz plane via reconstructing H-bonds. • The electron transfer from Ni to Ta promotes the alkaline seawater oxidation. • A neoteric strategy to tailor the interfacial H-bond mediated catalysis.