*3.1. Synthesis*

Perovskite-type mixed metal oxides LaMO3 (M = Mn or Fe) were synthesized by a three-step reactive grinding process:


Materials taken from step 2 and 3 are calcined for 3 h at 400 ◦C prior to characterization and catalytic performance evaluation, and are respectively named LaM\_HEBM and LaM\_LEBM.
