In situ self-growth of NiOOH/CrO₂ catalyst via constant current electrooxidation for urea oxidation reaction

In this study, the catalyst is generated in situ on the electrode surface, which breaks through the traditional electrode preparation methods. The Ni-Cr alloy is simply subjected to anodic leaching treatment in KSCN and KOH solutions, followed by activation treatment in a 1 M KOH and 0.33 M urea solution to complete the final step of electrode preparation. The urea oxidation reaction (UOR) achieves 10 mA cm⁻² at 1.362 V (RHE) and reaches the same current density at 1.355 V after 10 hours of chronopotentiometry (CP) aging. The Cdl values before and after CP-aging are 39.27 mF cm⁻² and 40.82 mF cm⁻². The excellent performance of the catalyst is attributed to the anti-poisoning ability of CrOOH and CrO₂, the synergistic effect between high-valent chromium and nickel, as well as the excellent electronic conductivity of Cr³⁺ and Cr⁴⁺.