First approach of fractals nickel-copper dendrites on stainless steel electrodes for ammonia oxidation to nitrogen monitored in operando by differential electrochemical mass spectroscopy

• Published in: Electrochimica acta 2024-11, Vol.504, p.144894, Article 144894
• Main Authors: Matamala-Troncoso, Felipe, Díaz-Coello, Sergio, Martínez, Francisco, Barrientos, Herna, Lisoni, Judit, Armijo, Francisco, Lozano, David, Pizarro, Jaime, Arévalo, María del Carmen, Pastor, Elena, Aguirre, María Jesús
• Format: Article
• Language: English
• Subjects: Ammonia oxidation; DEMS; Ni dendrites; Nickel copper alloy; Stainless steel
• ISSN: 0013-4686
• DOI: 10.1016/j.electacta.2024.144894

•Evaluation of synthesis parameter of fractal nickel-copper dendrites on stainless steel electrode.•Study of nickel-copper alloy morphologies in electrochemical applications.•Evaluation of electrochemical ammonia oxidation on stainless steel electrodes coated with fractal nickel-copper dendrites.•Reaction monitoring by differential electrochemical mass spectroscopy of ammonia oxidation gas products. Fractal nickel-copper dendrites were synthesized by electrochemical deposition (ECD) on a stainless steel electrode (SS/NiCu). The electrode surface was characterized using Field Emission Scanning Electron Microscopy (FE-SEM), X-ray diffractometry (XRD), and Raman spectroscopy. The Ni-Cu molar ratio and the time applied in the ECD method were studied, revealing that both are critical factors in modifying and controlling the surface morphology. The SS/NiCu electrodes show a higher density current response when exposed to ammonium hydroxide, reaching a limiting current density at concentrations above 0.050 M NH4OH. Ammonia oxidation reaction (AOR) was monitored in operando using differential electrochemical mass spectroscopy (DEMS). When a bias potential over +1.50 V (vs. RHE) was applied, the evolution of oxygen and NO was observed. However, N2 was the only oxidation product at a constant potential below +1.50 V (vs. RHE). Oxygen (O2) evolution was the main competitive reaction during the AOR. The results show that products are strongly dependent on the electrochemical perturbation applied. The study demonstrated that the SS/NiCu electrodes are suitable for AOR to N2 in high alkaline conditions. [Display omitted]