# Superprotonic Conduction in Donor Co‐Doped Perovskites

## TL;DR

This paper introduces a new method to boost proton conductivity in materials using donor co-doping, enabling efficient performance at intermediate temperatures.

## Contribution

The novel use of Mo/W donor co-doping in BaScO2.5 to achieve high proton conductivity at low temperatures.

## Key findings

- BaSc0.8Mo0.1W0.1O2.8 shows exceptional proton conductivity of 0.10 S cm−1 at 315°C.
- Donor co-doping increases proton concentration and mobility without raising activation energy.
- The material is chemically stable in CO2, O2, and H2 atmospheres.

## Abstract

Donor doping of oxygen‐deficient BaScO2.5 is an unexplored strategy for achieving high proton conductivity at intermediate temperatures of 200−400 °C. In this work, a new series of BaSc1−

x

−

y
Mo
x
W
y
O3−

δ
compounds was prepared via Mo/W donor co‐doping where x is the Mo content, y is the W content, and δ is the amount of oxygen vacancies. The present work reports the enhancement of proton conductivity by the Mo/W donor co‐doping of BaScO2.5. BaSc0.8Mo0.1W0.1O2.8 exhibits exceptional proton conductivity—0.10 S cm−
1 at 315 °C and 0.01 S cm−
1 at 193 °C—alongside outstanding chemical stability in CO2, O2, and H2 atmospheres. The high proton conductivity originates from the synergistic effects of abundant oxygen vacancies (δ = 0.2) and full hydration, yielding a high proton concentration, coupled with high proton diffusivity. The high diffusivity is attributable to the reduced proton trapping compared with acceptor and isovalent doping and overdoping due to higher proton concentration. In contrast to the acceptor co‐doping, the donor co‐doping does not increase the activation energy, resulting in lower activation energy and higher proton conductivity. These findings establish donor co‐doping into the oxygen‐deficient perovskites as a powerful design principle for next‐generation proton conductors with high proton conductivity at intermediate temperatures.

Ceramic proton conductors are promising materials for various applications such as fuel cells. Here, we report superprotonic conduction of BaSc0.8Mo0.1W0.1O2.8 created by donor Mo/W co‐doping into BaScO2.5 (e.g., 10−2 S cm−1 at 193 °C). The high proton conductivity is attributed to high carrier concentration and mobility. The present findings would open the new windows in the science and technology of donor co‐doped proton conductors.