In situ ion-exchange preparation and topological transformation of trimetal–organic frameworks for efficient electrocatalytic water oxidation

Abstract

Anion exchange membrane water electrolysis (AEMWE) with non-precious catalysts offers a promising route for industrial hydrogen production. However, the sluggish kinetics of anodic water oxidation hinder its efficiency and cost. We report herein a highly active two-dimensional trimetal–organic framework (NiCoFe–NDA) as a referential electrocatalyst for water oxidation. The as-prepared NiCoFe–NDA delivers a low overpotential of 215 mV at 10 mA cm⁻² with a small Tafel slope of 64.1 mV dec⁻¹ and exhibits excellent stability even at a high current density of 100 mA cm⁻² for 50 h without obvious activity attenuation. A home-made AEMWE using an anodic NiCoFe–NDA catalyst affords a cell voltage of only 1.8 V to drive a current density of 325 mA cm⁻² and performs robustly during continuous operation for over 100 h. During the anodic water oxidation, NiCoFe–NDA undergoes an in situ phase transformation, and the surface-reconstructed NiCoFe–NDA inherits its topological nanosheets and induces active surface-rich metal oxyhydroxides with abundant low-coordination catalytic environments, which would provide a positive multi-metal coupling effect to promote water oxidation. This work provides an organic–inorganic hybrid platform for designing high-efficiency electrocatalysts to advance water electrolysis technologies.