Metal - organic frameworks derived Ni 5 P 4 /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.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2022 Elsevier Inc. All rights reserved.)