Surface Acidity Dictates Proton Transport in WO₃/ZrO₂: Proton-Conductive Behavior and Mechanistic Insight.

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Inorganic proton conductors are vital for fuel cell technology but often exhibit limited conductivity, especially at low temperatures.
• Understanding proton conduction mechanisms is essential for designing improved materials.

Purpose of the Study:

• To investigate metal oxide solid acids as promising proton conductors.
• To synthesize and characterize WO3/ZrO2 (WZ) materials with varying surface acidities.
• To elucidate the relationship between surface acidity and proton conductivity.

Main Methods:

• Synthesis of WO3/ZrO2 (WZ) composites with controlled WO3 content.
• Measurement of proton conductivity across a range of temperatures.
• Theoretical calculations to understand conduction mechanisms.

Main Results:

• Proton conductivity of WZ samples strongly correlates with their surface acidity.
• WZ with the highest acidity achieved a conductivity of 3.27 × 10^-5 S cm^-1 at 14 °C.
• Theoretical calculations revealed enhanced water adsorption and lower O-H bond dissociation energy as key factors.

Conclusions:

• Tailoring surface acidity of metal oxides is an effective strategy for enhancing proton conductivity.
• WO3/ZrO2 demonstrates significant potential as a low-temperature proton conductor.
• Mechanistic insights provide a basis for rational design of future proton-conductive materials.