Ultrathin vanadium hydroxide nanosheets assembled on the surface of Ni–Fe-layered hydroxides as hierarchical catalysts for the oxygen evolution reaction.

Developing state-of-the-art non-noble metal catalysts for the oxygen evolution reaction holds a key to the production of electrolytic hydrogen. Herein, self-supported hierarchical NiFe LDH/VO(OH)₂ nanoflowers/nanosheets grown on a Ni foam have been synthesized via a two-step hydrothermal method. Numerous fine VO(OH)₂ nanosheets grown on NiFe LDH nanoflowers enlarge the contact area for the electrolyte penetration and facilitate ion diffusion, while the three-dimensional structure of the material also provides an extensive active surface area and plentiful accessible active sites. Moreover, the strong synergistic interaction between VO(OH)₂ and NiFe LDHs subtly modulates the electronic environment, accelerating the electron/charge transfer. As a result, the catalyst exhibits excellent electrochemical performance for OER giving a voltage of 1.51 V to achieve the current density of 100 mA cm⁻² and possessed a Tafel slope of 65 mV dec⁻¹ in 1.0 M KOH. In addition, the material exhibited remarkable long-term durability and stability during the 40 h measurement. This investigation provides a promising strategy for rationally designing high-efficiency metal electrocatalysts with hierarchical multi-dimensional nanostructures for OER. [ABSTRACT FROM AUTHOR]