Valence state modulation of Mn/FePO4 nanostructures for the oxygen reduction reaction

The oxygen reduction reaction (ORR) is the limiting factor in many renewable technologies, for example, metal-air batteries and fuel cells, that have received a lot of scientific attention. Herein, we first prepared Mn-doped FePO4 nanoparticles encased in phosphorus incorporated reduced graphene oxide (PhG) sheets. The electrocatalyst gets a significant boost in ORR activity via adjustment of the Mn valence state when the as-prepared m-MnFePO4@PhG is modified by the chemical reduction method. The optimized r-MnFePO4@PhG shows an impressive half-wave potential (E-1/2) of 0.73 V vs. RHE and limiting current density (J(L)) of 5.16 mA cm(-2) at 0.1 V (1600 rpm) which reach close to those of Pt/C (20 wt%) (E-1/2 = 0.77 V and J(L) = 5.51 mA cm(-2)). Moreover, the catalyst exhibits strong methanol tolerance and retains 94.7% of the original current density after similar to 14 h of testing under alkaline conditions.