pH-dependent proton conducting behavior in a metal-organic framework material.

Area of Science:

• Materials Science
• Chemistry
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) are crystalline porous materials with tunable properties.
• Proton conductivity in MOFs is crucial for applications like fuel cells.
• Developing efficient proton-conducting MOFs remains a significant challenge.

Purpose of the Study:

• To synthesize a novel proton-conducting MOF.
• To investigate the proton conductivity of the modified MOF under various conditions.
• To elucidate the mechanism of proton conduction.

Main Methods:

• Microwave-assisted solvothermal synthesis of Ni2(dobdc) MOF.
• Acidification of Ni2(dobdc) in sulfuric acid solutions at different pH.
• Proton conductivity measurements at varying temperature and relative humidity.
• Analysis of conduction mechanism and activation energy.

Main Results:

• A porous Ni2(dobdc) MOF was successfully synthesized.
• Acidification yielded proton-conducting frameworks, H(+)@Ni2(dobdc).
• The MOF at pH 1.8 exhibited high proton conductivity (2.2×10⁻² S cm⁻¹) at 80°C and 95% RH.
• Proton conduction followed the Grotthuss mechanism with low activation energy.

Conclusions:

• The synthesized H(+)@Ni2(dobdc) MOF demonstrates excellent proton conductivity.
• Protonated water clusters within the MOF pores facilitate conduction.
• This material shows promise for advanced electrochemical energy applications.