Polyoxometalated metal-organic framework superstructure for stable water oxidation

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Nonprecious catalysts are essential for cost-effective alkaline water electrolysis.
• Developing stable and highly active electrocatalysts remains a significant challenge.

Purpose of the Study:

• To engineer a novel grafted superstructure catalyst, MOF@POM, for enhanced alkaline water electrolysis.
• To investigate the catalytic mechanism and long-term stability of the MOF@POM catalyst.

Main Methods:

• Self-assembly of metal-organic framework (MOF) with polyoxometalate (POM).
• In situ electrochemical transformation of MOF into active metal (oxy)hydroxides.
• Electrochemical performance testing in alkaline electrolyte and anion exchange membrane water electrolyzer.
• In situ electrochemical spectroscopy and theoretical calculations for mechanistic studies.

Main Results:

• MOF@POM catalyst exhibits a low overpotential of 178 mV at 10 mA/cm².
• An anion exchange membrane water electrolyzer achieved 3 A/cm² at 1.78 V at 80°C.
• Demonstrated stable operation at 2 A/cm² for over 5140 hours at room temperature.
• Synergistic interactions between metal atoms facilitate fast electron transfer and stabilize active sites.

Conclusions:

• The MOF@POM superstructure is a highly efficient and stable nonprecious catalyst for alkaline water electrolysis.
• The catalyst's performance is attributed to synergistic metal interactions and stabilized active sites.
• This work offers a promising pathway for developing advanced electrocatalysts for sustainable hydrogen generation.