Ni/Co co-doped Fe(OH)3 nanosheet arrays on nickel foam as high-performance bifunctional electrocatalysts for oxygen evolution and urea oxidation via multimetallic synergy.

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.