NiFe Hydroxide Supported on Hierarchically Porous Nickel Mesh as a High-Performance Bifunctional Electrocatalyst for Water Splitting at Large Current Density.

The preparation of efficient and low-cost bifunctional catalysts with superior stability for water splitting is a topic of significant current interest for hydrogen generation. A facile strategy has been developed to fabricate highly active electrodes with hierarchical porous structures by using a two-step electrodeposition method, in which NiFe layered double hydroxide is grown in situ on a three-dimensional hierarchical Ni mesh (NiFe/Ni/Ni). The as-prepared NiFe/Ni/Ni electrodes demonstrate remarkable structural stability with high surface areas, effective gas transportation, and fast electron transfer. Benefiting from the unique structure, the self-supported NiFe/Ni/Ni electrodes exhibit overpotentials of 190 mV and 300 mV for the oxygen evolution reaction (OER) at current densities of 10 and 500 mA cm-2 , respectively. Furthermore, the self-supported NiFe/Ni/Ni electrodes also exhibit high performance in the hydrogen evolution reaction (HER) and excellent stability at a current density of 500 mA cm-2 for both OER and HER. Remarkably, using NiFe/Ni/Ni as both the cathode and anode for alkaline water electrolysis, a current density of 500 mA cm-2 is attained at a cell voltage of 1.96 V. Additionally, the water electrolyzer demonstrates superior stability even at a large current density (500 mA cm-2 ) when subjected to high temperatures.