Co2P encapsulated in N, O co-doped carbons as bifunctional electrocatalysts for oxygen evolution and reduction reactions

Exploring highly-efficient and low-cost non-precious metal electrocatalysts for electrochemical reactions such as oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is of crucial importance for clean and renewable energy technologies . Herein, we report the synthesis of Co 2 P encapsulated in N- and O- co-doped carbons (Co 2 P@NOCs), which can serve as excellent noble metal-free bifunctional electrocatalysts for OER and ORR in alkaline media . Especially, the Co 2 P@NOC-2 electrocatalyst exhibits a low overpotential of 330 mV to deliver the current density of 10 mA cm −2 for OER in 1.0 M KOH solution, with a small Tafel slope of 97 mV dec −1 . With respect to ORR activity, Co 2 P@NOC-2 gives positive onset ( E onset ) and half-wave ( E 1/2 ) potentials of 0.90 and 0.75 V ( vs. RHE) in 0.1 M KOH electrolyte, respectively. Additionally, it presents better methanol tolerance and long-term durability as compared to the commercial Pt/C (20  wt ·%) catalyst. The high electrocatalytic activity and good long-term stability toward OER and ORR can be attributed to the conductive heteroatoms-doped carbon layer , the embedded Co 2 P active sites and the synergistic effects between them. The strong synergism can significantly promote the electron transfer during the reaction and enhance the OER and ORR performance.