Coal Oxide as a Thermally Robust Carbon-Based Proton Conductor

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Practical solid-state electrochemical devices require inexpensive, thermally stable proton conductors.
• Graphene oxide (GO) is a known proton conductor but has limitations in thermal stability.

Purpose of the Study:

• To investigate coal oxide (CO) as a novel, cost-effective proton conductor.
• To evaluate the proton conductivity and thermal stability of CO compared to GO.

Main Methods:

• Coal was oxidized via a simple liquid-phase method to produce coal oxide (CO).
• The dispersibility of CO in water was assessed, attributed to surface carboxyl groups.
• Proton conductivity measurements were performed under varying humidity.
• Thermal stability was tested through annealing at 200 °C, followed by conductivity and capacitance performance evaluation.

Main Results:

• Coal oxide (CO) exhibited excellent dispersibility in water.
• CO demonstrated a proton conductivity of 3.9 × 10⁻³ S cm⁻¹ at 90% relative humidity, comparable to GO.
• CO showed significantly higher thermal stability than GO, retaining performance after annealing at 200 °C.

Conclusions:

• Chemically modified coal (CO) is a viable, inexpensive carbon-based proton conductor.
• CO offers superior thermal robustness compared to GO for electrochemical applications.
• This research highlights the potential of abundant coal resources for developing practical proton conductors for energy devices.