Ultrafast Room‐Temperature Synthesis of Self‐Supported NiFe‐Layered Double Hydroxide as Large‐Current–Density Oxygen Evolution Electrocatalyst

Abstract Water splitting is a promising sustainable technology to produce high purity hydrogen, but its commercial application remains a giant challenge due to the kinetically sluggish oxygen evolution reaction (OER). In this work, a time‐ and energy‐saving approach to directly grow NiFe‐layered double hydroxide (NiFe‐LDH) nanosheets on nickel foam under ambient temperature and pressure is reported. These NiFe‐LDH nanosheets are vertically rooted in nickel foam and interdigitated together to form a highly porous array, leading to numerous exposed active sites, reduced resistance of charge/mass transportation and enhanced mechanical stability. As self‐supported electrocatalyst, the representative sample (NF@NiFe‐LDH‐1.5‐4) shows an excellent large‐current–density catalytic activity for OER in alkaline electrolyte, requiring low overpotentials of 190 and 220 mV to reach the current densities of 100 and 657 mA cm−2 with a Tafel slope of 38.1 mV dec−1. In addition, NF@NiFe‐LDH‐1.5‐4 as an overall water splitting electrocatalyst can stably achieve a large current density of 200 mA cm−2 over 300 h at a low cell voltage of 1.83 V, meeting the requirement of industrial hydrogen production. This exceedingly simple and ultrafast synthesis of low‐cost and highly active large‐current–density OER electrocatalysts can propel the commercialization of hydrogen producing technology via water splitting.