Metal Hydroxide-Organic Framework Mediated Structural Reengineering Enables Efficient NiFe Interaction for Robust...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Nickel-iron layered double hydroxides (NiFe LDHs) are effective electrocatalysts for the alkaline oxygen evolution reaction (OER).
• The intrinsic metal-oxygen-metal (M-O-M) structure of NiFe LDHs limits nickel-iron interaction, impacting catalytic activity and long-term stability.
• Enhancing NiFe interaction is crucial for advancing OER electrocatalyst performance.

Purpose of the Study:

• To develop a modified NiFe LDH structure with improved NiFe interaction for enhanced OER performance.
• To investigate the structural and electronic effects of incorporating an organic linker into the NiFe LDH framework.
• To evaluate the electrocatalytic activity and stability of the novel material for the OER.

Main Methods:

• Synthesis of a NiFe hydroxide-organic framework (NiFe HOF) by modifying NiFe LDH with an organic linker.
• Electrocatalytic testing of NiFe HOF for the oxygen evolution reaction (OER) in an alkaline medium.
• Structural analysis to understand the metal-oxygen-metal bond evolution and NiFe interaction under OER conditions.
• Long-term stability testing in an anion exchange membrane electrolyzer.

Main Results:

• The NiFe HOF structure facilitates reconfigurable metal sites, leading to enhanced NiFe interaction and prolonged metal-oxygen bonds under OER conditions.
• The NiFe HOF exhibits a stimulated lattice oxygen mechanism, contributing to improved catalytic activity.
• A significantly reduced overpotential of 68 mV at 50 mA cm⁻² was observed for NiFe HOF compared to NiFe LDH.
• The NiFe HOF demonstrated ultralong stability (>1050 h at 1 A cm⁻²) with minimal attenuation (0.16 mV h⁻¹) in an anion exchange membrane electrolyzer.

Conclusions:

• The developed NiFe HOF effectively overcomes the limitations of NiFe LDH by enhancing NiFe interaction through structural modification.
• The NiFe HOF presents a promising electrocatalyst for the alkaline OER, offering superior activity and unprecedented stability.
• This work highlights the potential of hydroxide-organic frameworks for designing advanced electrocatalysts for energy conversion applications.