Co-Induced Electronic Optimization of Hierarchical NiFe LDH for Oxygen Evolution

Developing efficient and stable non-noble electrocatalysts for the oxygen evolution reaction (OER) remains challenging for practical applications. While nickel-iron layered double hydroxides (NiFe-LDH) are emerging as prominent candidates with promising OER activity, their catalytic performance is still restricted by the limited active sites, poor conductivity and durability. Herein, hierarchical nickel-iron-cobalt LDH nanosheets/carbon fibers (NiFeCo-LDH/CF) are synthesized through solvent-thermal treatment of ZIF-67/CF. Extended X-ray adsorption fine structure analyses reveal that the Co substitution can stabilize the Fe local coordination environment and facilitate the π-symmetry bonding orbital in NiFeCo-LDH/CF, thus modifying the electronic structures. Coupling with the structural advantages, including the largely exposed active surface sites and facilitated charge transfer pathway ensured by CF, the resultant NiFeCo-LDH/CF exhibits excellent OER activity with an overpotential of 249 mV at 10 mA cm^-1 as well as robust stability over 20 h.