Co-MOF-derived core-shell CoP@Co3O4 nanoparticle loaded N-doped graphene: An efficient catalyst for oxygen evolution reaction

Metal-organic frameworks (MOFs) and their derivatives have multiple advantages, such as controlled morphology and uniform distribution of elements, which can be served as a kind of excellent electrocatalyst. It is significant to balance the relationship between activity, conductivity and stability of catalyst for oxygen evolution reaction (OER). The construction of interface in composite materials is an important strategy for the preparation of catalyst for OER. In this paper, a novel Co-MOF (Co-MOF-NH2) was synthesized by hydrothermal method, which was mixed with melamine phosphate (P-MA) and calcined to obtain AIP-PMA composite material. For the first time, a one-step pyrolysis method was used to embed CoP nanoparticles into the Co3O4 shell and load them on the N-doped graphene layer. As a result, the unique morphology offered more dispersed active site and larger specific surface area, and demonstrated the highest catalytic activity and electrical conductivity. Density functional theory (DFT) calculation also showed that the formation of the interface between CoP and Co3O4 made the center of the d band of Co in AIP-PMA far away from the Fermi level, thus reducing the energy barrier released by O2 and resulting as excellent OER performance with 1.55 V potential at a current density of 10 mA cm-2. Furthermore, the graphene coating effectively shielded the catalyst, allowing it to remain stable over time.