MOFs derived NiFeP porous nanoflowers for boosted electrocatalytic water splitting

High-efficiency and stable non-precious metal electrocatalysts are of great significance to the development of the overall water splitting system in alkaline medium. Here, three-dimensional hierarchical NiFe-LDH-MOF nanoflowers with adjustable Ni/Fe ratio were synthesized by a simple hydrothermal method. Subsequently, the NiFe bimetallic based organic framework is obtained by the gas-phase anion exchanging strategy, and the corresponding phosphides MOF (NiFeP-MOF) is grown. These Ni–Fe phosphides-MOF catalysts show low potentials, small Tafel slopes, and excellent durability, accompanied by a low overpotential of 32 and 233 mV for hydrogen and oxygen evolution reactions to provide a current density of 10 mA cm−2, respectively, due to its large electrochemical surface area and 3D porous morphologies for electron and proton transfer, leading to efficient catalytic activities. It is worth noting that the symmetrical electrolyzer constructed by the NiFe-based phosphides MOFs demonstrate excellent water splitting performance, reaching a current density of 10 mA cm−2 at a relative low potential of only 1.54 V, which is superior to the precious metal RuO2||Pt/C electrocatalyst (1.57 V @ 10 mA cm−2). Density functional theory calculations prove that the outstanding overall hydrolysis of NiFeP-MOF benefits from its hierarchical porous structure, which facilitates the effective adsorption and disintegration of H2O molecule on the catalyst surface. This work provides a promising tactics to develop high efficiency electrocatalysts for practical using of overall water splitting system.