Proton-conducting solid oxide electrolysis cells (H-SOECs) have attracted lots of attention due to high efficiency, energy saving and environmental friendly. The ideal H-SOEC oxygen electrode materials are triple conducting oxide with mixing proton (H⁺), oxygen ion (O^2-) and electron (e^-) conductivity. Herein, the triple conductive oxide Pr₂NiO_4+δ (PNO)-based perovskite (Pr_0.9La_0.1)₂(Ni_0.8Cu_0.2)O_4+δ (PLNCu) is chosen as the oxygen electrode of H-SOEC with impressive electrochemical performance. Its crystal structure, physicochemical property and cell performance are discussed in detail. The thermal expansion coefficient of the PLNCu sample is 13.78×10^-6 K^-1, and the electrical conductivity is 258 S cm^-1 at 450 °C. Moreover, the polarization resistance of the single cell is as low as 0.056 Ω cm² and the current density at 1.3 V can reach 1.61 A cm^-2 at 750 °C, which shows the good electrochemical performance. 100 h of long-term testing also shows that the cell has good performance and structure stability. Therefore, this work highlights a novel oxygen electrode material (Pr_0.9La_0.1)₂(Ni_0.8Cu_0.2)O_4+δ for proton-conducting solid oxide electrolysis cells.

Proton conducting; Solid oxide electrolysis cells; Ruddlesden-Popper perovskite; Oxygen electrode; Electrochemical performance