Core@shell MOFs derived Co₂P/CoP@NPGC as a highly-active bifunctional electrocatalyst for ORR/OER

In this study, Co₂P/CoP hybrid nanoparticles (NPs) imbedded on the surface of core–shell metal–organic frameworks (MOFs) derived three-dimensional N, P co-doped graphitized carbon (Co₂P/CoP@NPGC) are prepared via direct pyrolysis of P-containing MOF precursors. P dopant dosage is tailored to adjust active sites and crystalline phases of Co₂P/CoP@NPGC. The active Co₂P and CoP NPs and the synergistic effect from the Co-Nx/C and Co-P/C active sites and porous NPGC make the dominant contributions to the ORR/OER. For ORR, the half-wave potential of Co₂P/CoP@NPGC-1 is 0.93 V, which is superior to that of Pt/C (E_1/2 = 0.875 V). As for OER, Co₂P/CoP@NPGC-1 displays a lower overpotential (ƞ = 340 mV) compared to RuO₂ (ƞ = 380 mV, at 10 mA cm⁻²). The Co₂P@CoOOH heterojunction guarantees intrinsic conductivity. Furthermore, doping with N and P can modify the surface electronic structure of catalyst to lower the energy of oxygen adsorption and dissociation, which are beneficial to enhance the ORR and OER activity. Additionally, its bifunctional activity parameter (ΔE) for ORR and OER is only 0.64 V, which is lower than that of Pt/C and RuO₂ (0.76 V). Therefore, this work proposes a new sight into constructing a competitive core–shell MOFs derived electrocatalyst for ORR/OER.