Acid-Corrosion-Induced Hollow-Structured NiFe-Layered Double Hydroxide Electrocatalysts for Efficient Water Oxidation

Highly active, cost-effective, and stable electrocatalyst for oxygen evolution reaction (OER) is of primary importance in electrochemical water splitting. Although the direct growth of active components on the substrate is an effective strategy to enhance the catalytic activity, the weak adhesion between active material and substrate tremendously hampers their long-term utilization with excellent performance. Herein, a three-dimensional (3D) hollow structure of NiFe-layered double hydroxide (NiFe LDH) on NiFe foam (NiFe LDH@NiFe) is designed via acid-corrosion-induced strategy. The self-supported electrode was obtained through a process based on an autologous NiFe foam, in which the electrode/gas/electrolyte interface and electrocatalyst/substrate interface are delicately engineered. Remarkably, the NiFe LDH@NiFe only needs an ultralow overpotential of 201 mV to deliver a current density of 10 mA cm–2 for OER in 1 M KOH electrolyte, along with superb stability. The high catalytic activity is attributed to the intimate connection between the nanosheet arrays and substrate, superior intrinsic activity, and fast electron transfer. More importantly, the excellent hydrophilicity and aerophobicity of NiFe LDH@NiFe enables significantly improved infiltration of electrolytes, quick release of oxygen bubbles, and remarkably enhanced charge transfer. Thus, the obtained NiFe LDH@NiFe holds promise for electrocatalytic applications. Finally, the growth mechanism of NiFe LDH@NiFe is investigated and discussed in detail.