High topological tri-metal phosphide of CoP@FeNiP toward enhanced activities in oxygen evolution reaction

The development of non-precious metal electrocatalysts with high activity, good durability and low cost to replace precious metal electrocatalysts is highly demanded for oxygen evolution reaction (OER). However, the higher overpotential, less catalytic sites and lower catalytic rate of precious metal electrocatalysts affect their practical application, which needs to be optimized from the aspects of structural design (e.g., specific morphology/particle size, geometric/electronic structures). In this study, we reported a high topological tri-metal phosphide of CoP@FeNiP derived from the composite structure of ZIF-67 twined on a FeNi-LDH shelled with ultrathin carbon networks (ZIF-67/FeNi-LDH) grown on a nickel foam. In the synthesis process of FeNi-LDH, the addition of polyvinylpyrrolidone (PVP) promoted the self-assembly of the topological structure of FeNi-LDH and further nucleation of the topological structure of the ZIF-67 precursor on FeNi-LDH. Besides, CoP@FeNiP inherits the topological structure of ZIF-67/FeNi-LDH. The obtained CoP@FeNiP/NF shows superior OER performance with a low overpotential of ∼283 mV at 100 mA cm-2, a low Tafel slope of ∼31.8 mV dec-1 and a conservation rate of catalytic activity of ∼98% after 110 h of continuous electrolysis at 10 mA cm-2. The remarkable activity of CoP@FeNiP/NF can be attributed to its unique structural features, such as the hierarchical morphology, large surface area, ultrathin carbon networks and the feature of phosphide, all of which simultaneously promote the OER process. The extraordinary catalytic activities and stability of CoP@FeNiP/NF are significant to meet the industrial requirements for bulk water electrocatalysis.