Fe₂P as cocatalyst for ultra-low Pt oxygen reduction reaction catalyst

The preparation of low Pt catalysts for oxygen reduction reaction (ORR) has been the focus research in fuel cell. Here, Pt&Fe₂P@NC with ultra-low Pt loading (∼2 wt% Pt, one tenth of the commercial 20 wt% Pt/C) is prepared by introducing Fe₂P cocatalyst into Pt-based catalyst through a simple two-step pyrolysis method. Pt&Fe₂P@NC shows excellent ORR electrocatalytic performance in 0.1 M KOH electrolyte with oxygen reduction peak potential of 0.91 V (vs. RHE), half-wave potential of 0.877 V (vs. RHE) and a nearly direct 4e reaction pathway. By comparing Pt@NC, Fe₂P@NC and Pt&Fe₂P@NC, Fe₂P plays a dual role in Pt&Fe₂P@NC: on one hand, Fe₂P, as an electron donor, transfers electrons to Pt, thus optimizing the adsorption of oxygen intermediates on Pt; on the other hand, Fe₂P has a Pt-like electron configuration and can also serve as an active site to co-catalyze the ORR together with Pt. This study provides a new strategy for the preparation of ultra-low Pt catalysts for ORR.