Cellulose Proton Conductor: Both Sulfonic Acid and Hydrophobic Group Functionalization Enable High Proton...

Area of Science:

• Materials Science
• Electrochemistry
• Sustainable Chemistry

Background:

• Proton exchange membranes (PEMs) are crucial for energy devices like fuel cells.
• Environmental concerns surrounding per- and polyfluoroalkyl substances (PFAS) necessitate sustainable alternatives.
• Nafion is a representative but environmentally impactful PEM material.

Purpose of the Study:

• To develop an effective and environmentally conscious synthesis method for PEMs.
• To create cellulose-based PEMs with high proton conductivity and stability.
• To address the demand for greener materials in energy conversion technologies.

Main Methods:

• One-pot synthesis of cellulose-based PEMs (SC-1) from cellulose.
• Controlled variation of reactant feed molar ratios to tune ion exchange capacity.
• Characterization using 1H NMR spectra, titration, and elemental analysis.
• Evaluation of proton conductivity, water uptake, and acid resistivity.

Main Results:

• Successfully synthesized SC-1 with ion exchange capacity from 1.07-1.49 mmol g⁻¹.
• Achieved a high degree of substitution (1.87-2.48) advantageous for membrane properties.
• Demonstrated maximum H⁺ conductivity exceeding 140 mS cm⁻¹ at 60 °C.
• Reported suppressed water uptake (69%) and good acid resistivity in 2 M H₂SO₄.

Conclusions:

• The one-pot synthesis effectively produces highly proton conductive cellulose-based PEMs (SC-1).
• SC-1 exhibits excellent performance, comparable to state-of-the-art cellulose-based PEMs.
• This method offers a promising sustainable alternative to PFAS-based PEMs for energy applications.