The Performance of Ruddlesden–Popper (R-P) Structured Pr2–xSrxNi0.2Mn0.8O4 for Reversible Single-Component Cells

In view of high catalytic activity and oxygen vacancy concentration, Ruddlesden–Popper (R-P) structure oxide has been widely used as the electrode material for solid oxide fuel cells (SOFCs). Herein, three R-P structure oxides, Pr2–xSrxNi0.2Mn0.8O4 (x = 1, 1.2, and 1.5), are used as the semiconductor materials of single-component cells. The materials for the oxygen side are hybrid oxides consisting of R-P structure oxide and perovskite oxide. The hydrogen side was exposed to the reduction atmosphere before the test, and the perovskite structure disappeared and the lattice parameters of the R-P structure changed, resulting in the formation of a new R-P structure and MnO2 or NiMn alloy. In addition, Pr0.5Sr1.5Ni0.2Mn0.8O4 and reduced Pr0.5Sr1.5Ni0.2Mn0.8O4 exhibit the most content of oxygen vacancy. For a single-component fuel cell (SCFC), the cell performance increased with the decrease in Pr content. The SCFC composed of Pr0.5Sr1.5Ni0.2Mn0.8O4 shows the highest maximum power densities (Pmax), which reached 206.6 mW cm–2 at 700 °C. It is because the reduced Pr0.5Sr1.5Ni0.2Mn0.8O4 has the highest catalytic activity for hydrogen oxidation reaction (HOR). Furthermore, the Pmax at 700 °C can reach a value of 198.1 mW cm–2 in SOFC mode, and in the case of SOEC mode, the current density at 700 °C is as high as −390.8 mA cm–2 with an applied electrolysis voltage of 1.3 V for the reversible single-component cell (RSCC) with Pr0.5Sr1.5Ni0.2Mn0.8O4 as the semiconducting electrocatalyst.