Ni/Co co-doped Fe(OH)₃ nanosheet arrays on nickel foam as high-performance bifunctional electrocatalysts for oxygen...

The sluggish kinetics of the anodic oxygen evolution reaction (OER) and the low efficiency of the urea oxidation reaction (UOR)-coupled systems hinder the practical implementation of energy-efficient hydrogen production, mainly because efficient and low-cost bifunctional electrocatalysts remain scarce. Here, we report a ternary layered hydroxide (FCN-0.01) in which Ni and Co ions are co-doped into a Fe(OH)₃ matrix. The catalyst was fabricated on nickel foam by one-step room-temperature electrodeposition, forming three-dimensional cross-linked ultrathin nanosheet arrays with synergistically optimized composition and structure. In 1.0 M KOH, FCN-0.01 delivers an OER overpotential of 174 mV at 10 mA cm^-2, with a Tafel slope of 56.18 mV dec^-1, and maintains stable OER performance for 100 h. In a urea-containing electrolyte, it achieves a UOR driving potential of 1.332 V versus the reversible hydrogen electrode (vs. RHE), with a Tafel slope of 41.45 mV dec^-1.These metrics are far superior to those of pristine Fe(OH)₃. Combined experimental characterization and theoretical calculations reveal that the Fe-Co-Ni system reconstructs the electronic structure of active sites through bridging oxygen, thereby optimizing oxygen-intermediate adsorption and lowering the free-energy barriers of both electrocatalytic reactions. This work demonstrates a high-performance, low-cost bifunctional electrocatalyst and offers a strategy for precisely regulating intermediate adsorption through multimetallic synergy and three-dimensional structural engineering.