Binary Metal Phosphides with MoP and FeP Embedded in P,N-Doped Graphitic Carbon As Electrocatalysts for Oxygen Reduction

Binary metal phosphides, a new class of nonprecious catalysts, have drawn tremendous attention in recent years for their synergistic interactions between different components. Herein, a novel in situ phosphorization and simultaneous graphitization strategy is developed to intentionally construct MoP-FeP hybrids with multiple active sites embedded in P,N-doped graphitic carbon (MoP-FeP/GC) as an effective electrocatalyst for oxygen reduction reaction (ORR). A macroporous amino phosphonic acid chelating resin was employed as phosphorus nitrogen and carbon resources. According to the strong coordination between the central metal and functional groups, H3P(Mo3O10)(4) and FeCl3 were successively introduced into the backbone of the resin to form a resin-P(Mo3O10)(4)(3-)-Fe3(+) precursor. After one-step pyrolysis, the highly dispersed MoP and FeP particles were achieved in situ. Simultaneously, the resin carbon was converted into graphitic carbon coupled with P,N codoping. As expected, the MoP-FeP/GC catalyst displays superior ORR activity to individual MoP and FeP, indicating a strong synergistic effect. The onset potential and half wave potential for MoP-FeP/GC are 0.91 and 0.75 V, respectively, which achieve the comparable level to those of state-of-the-art 20% Pt/C catalyst in alkaline electrolyte. This approach is simple and scalable, which opens an avenue for the rational design of binary metal phosphides as the nonprecious metal catalysts for ORR.