Ruddlesden–Popper-Structured (Pr0.9La0.1)2(Ni0.8Cu0.2)O4+δ: An Effective Oxygen Electrode Material for Proton-Conducting Solid Oxide Electrolysis Cells

Proton-conducting solid oxide electrolysis cells (H-SOECs) have attracted a lot of attention due to their high efficiency, energy-saving ability, and environmental friendliness. The ideal H-SOEC oxygen electrode materials are triple-conducting oxides with mixed proton (H+), oxygen ion (O2–), and electron (e–) conductivity. Herein, the triple conductive oxide Pr2NiO4+δ (PNO)-based perovskite (Pr0.9La0.1)2(Ni0.8Cu0.2)O4+δ (PLNCu) is chosen as the oxygen electrode of the 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 good electrochemical performance. A 100 h long-term test also shows that the cell has good performance and structural stability. Therefore, this work highlights a novel oxygen electrode material (Pr0.9La0.1)2(Ni0.8Cu0.2)O4+δ for proton-conducting solid oxide electrolysis cells.