Attempted preparation of La_0.5Ba_0.5MnO_3−δ leading to an in-situ formation of manganate nanocomposites as a cathode for proton-conducting solid oxide fuel cells

A La_0.5Ba_0.5MnO_3−δ oxide was prepared using the sol–gel technique. Instead of a pure phase, La_0.5Ba_0.5MnO_3−δ was discovered to be a combination of La_0.7Ba_0.3MnO_3−δ and BaMnO₃. The in-situ production of La_0.7Ba_0.3MnO_3−δ+BaMnO₃ nanocomposites enhanced the oxygen vacancy (V_O) formation compared to single-phase La_0.7Ba_0.3MnO_3−δ or BaMnO₃, providing potential benefits as a cathode for fuel cells. Subsequently, La_0.7Ba_0.3MnO_3−δ+BaMnO₃ nanocomposites were utilized as the cathode for proton-conducting solid oxide fuel cells (H-SOFCs), which significantly improved cell performance. At 700 ℃, H-SOFC with a La_0.7Ba_0.3MnO_3−δ+BaMnO₃ nanocomposite cathode achieved the highest power density (1504 mW·cm⁻²) yet recorded for H-SOFCs with manganate cathodes. This performance was much greater than that of single-phase La_0.7Ba_0.3MnO_3−δ or BaMnO₃ cathode cells. In addition, the cell demonstrated excellent working stability. First-principles calculations indicated that the La_0.7Ba_0.3MnO_3−δ/BaMnO₃ interface was crucial for the enhanced cathode performance. The oxygen reduction reaction (ORR) free energy barrier was significantly lower at the La_0.7Ba_0.3MnO_3−δ/BaMnO₃ interface than that at the La_0.7Ba_0.3MnO_3−δ or BaMnO₃ surfaces, which explained the origin of high performance and gave a guide for the construction of novel cathodes for H-SOFCs.