Superprotonic Conduction in Donor Co-Doped Perovskites.

Area of Science:

• Materials Science
• Solid State Chemistry
• Electrochemistry

Background:

• Proton conductivity in ceramic materials is crucial for electrochemical applications like fuel cells.
• Oxygen-deficient perovskites offer potential for proton conduction but require optimization.
• Donor doping is an underexplored strategy for enhancing proton conductivity in these materials.

Purpose of the Study:

• To investigate the effect of Mo/W donor co-doping on the proton conductivity of oxygen-deficient BaScO2.5.
• To explore the potential of this doping strategy for achieving high proton conductivity at intermediate temperatures (200-400 °C).
• To understand the relationship between doping, oxygen vacancies, hydration, and proton transport properties.

Main Methods:

• Synthesis of a new series of BaSc1-x-yMoxWyO3-δ compounds using Mo/W donor co-doping.
• Characterization of crystal structure and oxygen vacancy concentration (δ).
• Measurement of proton conductivity and chemical stability under various atmospheres (CO2, O2, H2).

Main Results:

• BaSc0.8Mo0.1W0.1O2.8 exhibited exceptional proton conductivity (0.10 S cm⁻¹ at 315 °C and 0.01 S cm⁻¹ at 193 °C).
• The material demonstrated outstanding chemical stability in CO2, O2, and H2 atmospheres.
• High proton conductivity was attributed to abundant oxygen vacancies (δ=0.2), full hydration, high proton concentration, and enhanced proton diffusivity.
• Donor co-doping resulted in lower activation energy compared to acceptor co-doping.

Conclusions:

• Donor co-doping of oxygen-deficient perovskites is a highly effective strategy for enhancing proton conductivity.
• BaSc0.8Mo0.1W0.1O2.8 represents a promising material for intermediate-temperature proton conductors.
• This approach provides a powerful design principle for developing next-generation proton-conducting materials.