Freestanding Cactus-Like Dual-Phase Bimetallic Metal-Organic Framework as a High-Efficiency Electrocatalyst for Water Oxidation

Realizing a high-efficiency electrochemical oxygen evolution reaction (OER) is a great challenge in water splitting and metal-air battery fields due to the slow reaction kinetics. Herein, a synchronous dual-phase synthetic strategy is developed to successfully construct a cactus-like dual-phase bimetallic metal- organic framework (MOF) on a nickel foam (NF) substrate (noted as NiFe-MOF@NF). It is constituted by Ni-main NiFe-MOF and Fe-main NiFe-MOF. When functioning as an anode, the freestanding cactus-like dual-phase NiFe-MOF@NF catalyst merely requires a lower overpotential of 277 mV to supply 100 mA cm-2 with robust stability (90% retainment of initial current density after 24 h chronoamperometry measurement). Density functional theory calculations on the NiFe-MOF@NF catalyst reveal that the combination of Ni and Fe has efficiently modulated the electron configuration of metal centers and optimized the absorption/desorption of OER oxygen-containing intermediates. Thus, we demonstrate a novel synchronous dual-phase synthetic strategy to engineer freestanding dual-phase electrocatalysts, which feature multiple synergetic effects considerably boosting OER performance for optimizing the energy conversion and storage system.