Spray-Pyrolytic Tunable Structures of Mn Oxides-Based Composites for Electrocatalytic Activity Improvement in Oxygen Reduction

Hybrid nanomaterials based on manganese, cobalt, and lanthanum oxides of different morphology phase compositions were prepared using a facile single-step ultrasonic spray pyrolysis (USP) process tested as electrocatalysts for oxygen reduction reaction (ORR). The structural morphological characterizations completed by XRD SEM-EDS. Electrochemical performance was characterized cyclic voltammetry linear sweep in rotating disk electrode assembly. All synthesized materials found electrocatalytically active ORR alkaline media. Two manganese oxide states incorporated into Co3O4 matrix, δ-MnO2 at 500 600 °C (II,III) oxide-Mn3O4 800 °C. difference crystalline structure revealed flower-like nanosheets birnessite-MnO2 well-defined spherical nanoparticles material Mn3O4. responses indicate that the mechanism follows preceding step MnO2 to MnOOH. calculated number electrons exchanged hybrid demonstrate four-electron pathway high electrocatalytic activity towards ORR. comparison molar catalytic activities points out importance composition synergy Co Mn is superior Co3O4/La2O3 pristine oxide. results reveal are promising