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

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.

Automated summary

The study presents a highly active two-dimensional trimetal-organic framework (NiCoFe-NDA) as a referential electrocatalyst for water oxidation, demonstrating excellent stability and low overpotential at high current density. An AEMWE system using NiCoFe-NDA catalyst exhibits high efficiency and stability.