Metal - organic frameworks derived Ni5P4/NC@CoFeP/NC composites for highly efficient oxygen evolution reaction

As an efficient non-precious metal catalyst for the oxygen evolution reaction (OER), phosphides suffer from poor electrical conductivity , so it is still a challenge to reasonably design their structures to further improve their conductivity and OER performances. Here, we present a novel Ni 5 P 4 / N -doped carbon@CoFeP/ N -doped carbon composite (Ni 5 P 4 /NC@CoFeP/NC) as electrocatalysts for OER. This elaborate structure consists of Ni 5 P 4 /NC derived from Ni-MOF and CoFeP/NC derived from CoFe-Prussian blue analog MOF (Co-Fe PBA). The cube-like CoFeP/NC are scattered and uniformly coated on the sheet of Ni 5 P 4 /NC flowers. Among them, NC can enhance the conductivity of phosphides, while CoFeP/NC can increase the electrochemical active area, which benefit the properties of Ni 5 P 4 /NC@CoFeP/NC. Notably, the Ni 5 P 4 /NC@CoFeP/NC catalyst possesses outstanding OER performances with a low overpotential of 260 and 303 mV at a current density of 10 and 100 mA·cm −2 , an ultra-low Tafel slope of 31.1 mV·dec -1 and excellent stability in 1 M KOH. XPS analysis shows that proper chemical composition promotes the oxidation of transition metal species and the chemisorption of OH – , thus accelerating the OER kinetics. Therefore, this work provides a hopeful method for designing and preparing transition metal phosphide/carbon composite as OER electrocatalysts.