Hierarchical Spiked Co0.85Se Microcrystals on Nickel Foam as an Efficient Electrocatalyst for Urea Oxidation Reaction

We report the facile synthesis of hierarchical spiked cobalt selenide (Co0.85Se) microcrystals grown on nickel foam (NF) via a hydrothermal method followed by selenization. Derived from cobalt hydroxyl fluoride (Co(OH)F) microcrystals, the resulting Co0.85Se structures exhibit a robust architecture with well-defined spikes that offer abundant active sites and promote efficient charge transfer, thereby enhancing their electrocatalytic bifunctional activity toward the oxygen evolution reaction (OER) and urea oxidation reaction (UOR). The Co0.85Se/NF electrode delivers low overpotentials of 357 mV for OER and 236 mV for UOR at 100 mA cm−2. Furthermore, it exhibits a small Tafel slope (34.3 mV dec−1) and excellent durability for 24 h at 100 mA cm−2 during UOR. This simple and cost-effective strategy highlights the potential of hierarchical spiked Co0.85Se microcrystals as highly efficient electrocatalysts for urea-assisted OER and related sustainable energy conversion applications.