A Petal-like Structured NiCuOOH-NF Electrode by a Sonochemical Combined with the Electrochemical Method for Ammonia Oxidation Reaction

Direct electrochemical oxidation, as an economical and efficient method, has recently received increasing attention for ammonia-nitrogen wastewater treatment. Developing a low-cost, efficient catalytic electrode is the key to solve the problem of sluggish ammonia oxidation reaction (AOR) kinetics. In this study, a three-dimensional (3D) Ni foam electrode coated with NiCuOOH petal-like cluster structures was prepared using a simple sonochemical method combined with a surface electrochemical reconstruction strategy. This structure has a large surface area and abundant NiCuOOH active sites, giving a good premise for extraordinary electrocatalytic activity of AOR. The results show that the maximum current density for AOR reaches 97.8 mA cm⁻² at 0.60 V vs. saturated calomel electrode (SCE). Additionally, 96.53% of NH₄⁺-N removal efficiency and 63.12% of TN removal efficiency were acquired in the electrolysis system based on the NiCuOOH-NF electrode, as well as a good stability for at least 24 h. It is a promising flow-through anode for the clean treatment of ammonia-nitrogen wastewater.