Nonmetal Organic Frameworks Exhibit High Proton Conductivity.

Area of Science:

• Materials Science
• Chemistry
• Chemical Engineering

Background:

• Porous materials like metal-organic frameworks (MOFs) and porous organic salts are investigated for proton conduction.
• Isoreticular nonmetal organic frameworks (N-MOFs) represent a new subclass of porous materials designed using crystal structure prediction (CSP).

Purpose of the Study:

• To synthesize and characterize novel, water-stable halide N-MOFs.
• To evaluate the proton conductivity of these new N-MOF materials.
• To investigate the effect of halide composition on proton conductivity.

Main Methods:

• Synthesis of two porous, isostructural, and water-stable halide N-MOFs.
• Measurement of proton conductivity under varying temperature and humidity conditions.
• Comparison of conductivity with existing porous materials and Nafion.

Main Results:

• The synthesized N-MOFs exhibit good proton conductivity, reaching up to 1.1 × 10^-1 S cm^-1 at 70 °C and 90% relative humidity.
• Proton conductivity is influenced by the type of halide present in the N-MOF structure.
• The bromide N-MOF (TTBT.Br) demonstrates conductivity comparable to Nafion, outperforming many MOFs and porous organic salts.

Conclusions:

• This study presents the first investigation of proton conductivity in N-MOFs.
• The developed halide N-MOFs are promising candidates for proton-conductive applications.
• Tailoring halide composition is a viable strategy to enhance proton conductivity in N-MOFs.