Fe–Ni Layered Double Hydroxide Arrays with Homogeneous Heterostructure as Efficient Electrocatalysts for Overall Water Splitting

Design and synthesis of highly efficient, stable, and low-cost catalysts have a crucial role in the study of electrolytic water. In this work, a novel Fe–Ni layered double hydroxide (LDH) material with homogeneous heterostructures is successfully synthesized by a two-step hydrothermal method. Compared with the ordinary Fe–Ni LDH arrays prepared by one step, this structure has a rougher surface, so it has a more extensive active area, thus providing more active sites. Due to the synergistic effect of different elements and more exposure of active sites, the catalytic effect of this material for water splitting is outstanding. The post-optimized FeNi@FeNi electrode exhibits extraordinary OER (oxygen evolution reaction) and HER (hydrogen evolution reaction) performance with OER overpotentials of 193, 231, and 306 mV and HER overpotentials of 127, 173, and 253 mV when the current density is 10, 20, and 50 mA·cm–2, respectively. The improved electrolytic water performance reveals that the design of homogeneous heterostructures is maybe an alternative route to exploit high-efficiency catalysts and promote the application of nonprecious metal catalytic materials.