In Situ Growth of Self-Supporting MOFs-Derived Ni₂P on Hierarchical Doped Carbon for Efficient Overall Water Splitting

Abstract

The in situ growth of metal organic framework (MOF) derivatives on the surface of nickel foam is a novel type of promising self-supporting electrode catalyst. In this paper, this work reports for the first time the strategy of in situ growth of Ni-MOF, where the metal source is purely provided by a nickel foam (NF) substrate without any external metal ions. MOF-derived Ni2P/NPC structure is achieved by the subsequent phosphidation to yield Ni2P on porous N, P-doped carbon (NPC) backbone. Such strategy provides the as-synthesized Ni2P/NPC/NF electrocatalyst an extremely low interfacial steric resistance. Moreover, a unique three-dimensional hierarchical structure is achieved in Ni2P/NPC/NF, providing massive active sites, short ion diffusion path, and high electrical conductivity. Directly applied as the electrode, Ni2P/NPC/NF demonstrates excellent electrocatalytic performance towards both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), with low overpotentials of only 58 mV and 208 mV to drive 10 mA cm−2, respectively, in 1 M KOH. Furthermore, Ni2P/NPC/NF acting as the overall water splitting electrodes can generate a current density of 10 mA cm−2 at an ultralow cell voltage of 1.53 V. This simple strategy paves the way for the construction of self-supporting transition metal-based electrocatalysts.

Keywords

• in situ growth
• self-supporting
• metal–organic framework
• Ni₂P/NPC
• overall water splitting