Constructing three-dimensional NiFe binary aerogel as anodic electrocatalyst for oxygen evolution reaction

The three-dimensional core-shell NiFe binary aerogel was facilely synthesized from the reduction-gelation method, and functioned as highly efficient anodic electrocatalyst for alkaline oxygen evolution. • Core-shell structured NiFe aerogel is facile constructed by one-step gelation. • Three dimensional structure provides more active sites and better conductivity. • Incorporation of metal cores and hydroxide shells contributes to the high activity. • A low overpotential of 258 mV is observed for the current density of 50 mA cm -2 . Designing highly active and stable anodic electrocatalysts is of great essentiality to improve the efficiency for alkaline water electrolysis. Metal aerogels with three-dimensional structure are developing fast recently as efficient electrocatalysts but research efforts mainly focus on noble metal-based aerogels. Herein, the nonprecious NiFe aerogel is synthesized from a fast metal salt reduction-gelation method. The three-dimensional NiFe aerogel was assembled from nanosized branches, which contained NiFe alloy nanoparticles as the cores and NiFe hydroxide nanosheets as the shells. The porous NiFe aerogel can provide more surface sites and benefit the mass/charge transfer, as well as the low crystallinity in structure can provide more active sites. As the result, this NiFe aerogel demonstrated remarkable electrocatalytic activity with low overpotential of 267 mV at 50 mA cm -2 and good durability for alkaline oxygen evolution reaction, which is among the best transition metal-based OER electrocatalysts. Thus, this NiFe aerogel holds good potentials for alkaline water oxidation and brings a novel member to the family of metal aerogels.