Solution combustion synthesis of LaxSm1−xMn2O5 nanoparticles and their electrocatalytic performances for Al-air batteries.

Graphical abstract Pure-phase La x Sm 1-x Mn 2 O 5 (x = 0.1,0.3, 0.5) was successfully prepared; Outstanding oxygen reduction activity for La x Sm 1-x Mn 2 O 5 (x = 0.1,0.3, 0.5), as is shown in Koutecky–Levich plots. Highlights • Pure-phase La x Sm 1−x Mn 2 O 5 were firstly achieved through one step calcined solution combustion synthesis with high yield. • The main impact of La/Sm is the amount of surface adsorbed oxygen and surface Mn4+ ions as revealed by XPS results. • The La 0.1 Sm 0.9 Mn 2 O 5 exhibited the highest activity, which has an appropriate ratio between oxygen vacancies and Mn3+. • The cell produced with La 0.1 Sm 0.9 Mn 2 O 5 exhibits flat discharge curves in 40 h above 1.5 V. Abstract Compared the most reported synthesis methods, a series of La x Sm 1−x Mn 2 O 5 (x = 0, 0.1, 0.3, 0.5) catalysts were first synthesized through sol-gel solution combustion synthesis with a short cycle and high yield. The main impact of different La/Sm molar ratios is the amount of surface adsorbed oxygen (O ads) and surface Mn4+ ions as revealed by XPS results. Electrochemical properties are characterized by rotating disk electrode (RDE) and the full dischargeable Al-air battery with 4 M NaOH electrolyte. The measurements of RDE reveal that the electron transfer number of La x Sm 1−x Mn 2 O 5 (x = 0, 0.1, 0.3, 0.5) are all closed to 4, and the sample prepared with x = 0.1 possesses the most excellent electrocatalytic activity for oxygen reduction reaction (ORR) and good discharge performance in alkaline medium. All of the above results indicate that the La x Sm 1−x Mn 2 O 5 (x = 0, 0.1, 0.3, 0.5) are promising catalysts with a high catalytic activity toward ORR. [ABSTRACT FROM AUTHOR]