Electrocatalytic oxidation of ammonia in the neutral medium using Cu2O.CuO film immobilized on glassy carbon surface

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Switzerland), 2021-09, Vol.897, p.115592, Article 115592
• Main Authors: Shabik, Md. Fazle, Hasan, Md. Mahmudul, Alamry, K.A., Rahman, Mohammed M., Nagao, Yuki, Hasnat, Mohammad A.
• Format: Article
• Language: English
• Subjects: Ammonia; Ammonia oxidation; Chemical reactions; Copper; Copper oxide film; Copper oxides; Electrocatalysis; Electrode polarization; Electrokinetics; Electron transfer; Glassy carbon; Oxidation; Oxide coatings; Silver chloride; Tafel analysis; X ray photoelectron spectroscopy
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/j.jelechem.2021.115592

Enhanced catalytic response towards ammonia oxidation was observed at Cu2O.CuO-GCE electrode. Ammonia undergoes 3 electron transfer reaction to produce N2 as the end product. The first electron transfer was evaluated to be the rate determining step, therefore, the reaction intermediates (NH2 ads, NHads, Nads) doesn’t control the rate of reaction. [Display omitted] •Sustaining the stability of the electrode is the main challenge in electrochemical oxidation of NH3.•We discuss the role of mixed Copper oxides (CuO-Cu2O) on Glassy Carbon electrode for NH3 oxidation.•The modified electrode shows good catalytic stability with increasing NH3 concentration.•Neutral medium is found to be most favorable for NH3 oxidation at CuO-Cu2O-GCE electrode. Electrocatalytic ammonia oxidation reaction (AOR) was executed on the copper oxide layer, electrochemically deposited on a glassy carbon electrode (GCE) surface. The XPS analysis revealed that the oxide film contains 80% Cu(I) and 20% Cu(II) species. The EIS analysis suggests that the resultant surface can catalyze ammonia oxidation reactions efficiently. The as prepared GCE-Cu2O.CuO favored the neutral medium for executing AOR with a degradation rate of 3.76 × 10−4 mol min−1 cm−2. Kinetic investigation shows that ammonia oxidation involves a three electron transfer first-order reaction. Tafel analysis of current–potential polarization curves indicates that species such as NH3 or NHads and NH2ads intermediates do not influence the reaction rate, which made the electrode unique for carrying out AOR. The formal potential value of AOR was evaluated to be ~0.7 V vs Ag/AgCl (sat.KCl) having standard rate constant (k°) of 5.52 × 10−6 cm/s.