Barium-doped Pr₂Ni_0.6Cu_0.4O_4+δ with triple conducting characteristics as cathode for intermediate temperature proton conducting solid oxide fuel cell

Proton conducting solid oxide fuel cell (H-SOFC) is an emerging energy conversion device, with lower activation energy and higher energy utilization efficiency. However, the deficiency of highly active cathode materials still remains a major challenge for the development of H-SOFC. Therefore, in this work, K₂NiF₄-type cathode materials Pr_2−xBa_xNi_0.6Cu_0.4O_4+δ (x = 0, 0.1, 0.2, 0.3), single-phase triple-conducting (e⁻/O²⁻/H⁺) oxides, are prepared for intermediate temperature H-SOFCs and exhibit good oxygen reduction reaction activity. The investigation demonstrates that doping Ba into Pr_2−xBa_xNi_0.6Cu_0.4O_4+δ can increase its electrochemical performance through enhancing electrical conductivity, oxygen vacancy concentration and proton conductivity. EIS tests are carried at 750 °C and the minimum polarization impedances are obtained when x = 0.2, which are 0.068 Ω·cm² in air and 1.336 Ω·cm² in wet argon, respectively. The peak power density of the cell with Pr_1.8Ba_0.2Ni_0.6Cu_0.4O_4+δ cathode is 298 mW·cm⁻² at 750 °C in air with humidified hydrogen as fuel. Based on the above results, Ba-doped Pr_2−xBa_xNi_0.6Cu_0.4O_4+δ can be a good candidate material for SOFC cathode applications.