Developing a Unique Hydrogen-Bond Network in a Uranyl Coordination Framework for Fuel Cell Applications.

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Developing solid electrolytes for intermediate-temperature proton exchange membrane fuel cells (IT-PEMFCs) is crucial for durable power generation.
• Achieving persistent high anhydrous proton conductivity in crystalline materials remains a significant challenge.

Purpose of the Study:

• To propose a novel uranyl-based coordination polymer for efficient anhydrous proton conduction.
• To investigate the potential of this material as a practical electrolyte in IT-PEMFCs.

Main Methods:

• Synthesis of a uranyl-based coordination polymer, UO2(H2PO3)2(C3N2H4)2 (HUP-3).
• Characterization of its crystal structure and hydrogen-bonded network.
• Measurement of anhydrous proton conductivity across a wide temperature range (-40-170 °C).
• Assembly and testing of a H2/O2 fuel cell using HUP-3 as the electrolyte.

Main Results:

• HUP-3 exhibits stable and efficient anhydrous proton conductivity from -40 °C to 170 °C.
• The material forms a dense hydrogen-bonded network utilizing axial uranyl oxo atoms.
• The assembled fuel cell achieved a high electrical power density of 11.8 mW·cm⁻² at 170 °C.
• The fuel cell demonstrated stable operation for over 12 hours without significant power loss.

Conclusions:

• The novel uranyl-based coordination polymer HUP-3 shows excellent potential as a solid electrolyte for IT-PEMFCs.
• Its unique structure facilitates high anhydrous proton conductivity, enabling high power density and durability.
• This work offers a promising pathway for developing advanced fuel cell technologies.