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 oxygen vacancy 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 ^oC, an H-SOFC with a La_0.7Ba_0.3MnO_3-δ+ BaMnO₃ nanocomposite cathode achieved the highest power density yet recorded for H-SOFCs with manganate cathodes: 1504 mW cm^-2. This performance was much greater than the 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 at the La_0.7Ba_0.3MnO_3-δ or BaMnO₃ surfaces, which explained the origins of the high performance and gave a guide for the construction of novel cathodes for H-SOFCs.