Unique three-dimensional nanoflower-like NiCu electrodes constructed by Co, S co-doping for efficient ammonia oxidation reaction

Nowadays, ammonia–nitrogen has been brought into focus for its hazards to the ecological environment. Electrocatalytic oxidation technology, with easy-to-operate and environmental friendliness, is expected to be applied to degrade ammonia–nitrogen. However, the key issues are the sluggish kinetics and high overpotential in ammonia oxidation reaction (AOR). In this work, a unique three-dimensional nanoflower-like structure electrode was constructed by Co, S co-doping NiCu for catalyzing AOR. This electrode provides a huge contact area in the active substance/electrolyte interface, greatly shortening the ion transport paths. Electrochemical tests confirmed that the Ni₁Cu₁Co_0.5-S-T/CP electrode obtained a high current density of 121.1 mA/cm² at 1.65 V vs RHE, a low onset potential of 1.241 V and demonstrated an excellent stability for at least 12 h. In the 8-hour ammonia–nitrogen removal experiment, a removal rate of 98.07 % and a high N₂ selectivity of 81.21 % were obtained. This work demonstrated that it was expected to provide an eco-friendly method for ammonia–nitrogen wastewater treatment based on the electrode.