Loose spherical FeOOH/MnO nanoarrays from a simple in situ hydrothermal method for enhanced oxygen evolution electrocatalysis

The development of abundant, low-cost, stable and efficient non-precious metal OER electrocatalysts is of great significance in large-scale water splitting for hydrogen production. Herein, loose spherical (Spherical-like composed of loose nanoarrays) MnFe bimetal oxide nanoarrays based on nickel foam were successfully synthesized by a simple in situ hydrothermal method. The loose nanoarrays facilitate water adsorption and exposure of active sites, enabling the catalyst to exhibit excellent electrocatalytic OER activity in alkaline media with an overpotential of 209 mV and a Tafel slope of 70 mV·dec−1. The addition of Fe greatly improves the electrical conductivity of the composites and the Fe site as the main active site, which together to the enhanced catalytic performance of FeOOH/MnO@NF (FeOOH/MnO In situ growth on Nickel Foam). In addition, the low crystallinity characteristic of the material is favorable for lattice distortion shrinkage, and the formation of Fe/Mn-O sites can accelerate the charge transfer rate, thereby accelerating the OER process. Meanwhile, the results of density functional theory calculations show that due to the strong interaction of electrons between the heterostructure, the displacement of the d-band center of the metal atom and the enhanced density of states near the Fermi level can adjust the binding energy intensity, which can affect the OER process, thereby improving the electrocatalytic performance. The findings broaden the exploration avenues of bimetallic oxyhydroxides as materials for water electrolysis and provides a new strategy for energy conversion and storage of sustainable energy. The development of stable and efficient non-precious metal OER electrocatalysts is crucial for large-scale water splitting to hydrogen production. To this end, Fe and Mn atoms with strong conductivity and with good water absorption can be introduced into the catalytic system to improve the OER performance. But, the real active center in the composite material is not very clear. Therefore, to study the role of atoms with Fe and Mn in the catalytic process is of self-evident importance. Herein, loose spherical FeOOH/MnO nanoarrays based on nickel foam has been successfully synthesized by a simple in situ hydrothermal method. More importantly, the heterostructure FeOOH/MnO has significant electrocatalytic activity with a low overpotential of 209 mV and small Tafel slope of 70 mV·dec−1. That is because the loose nanoarrays with large specifi