Electro-Oxidation of Ammonia over Copper Oxide Impregnated γ-Al₂O₃ Nanocatalysts

• Main Authors: Safia Khan, Syed Sakhawat Shah, Mohsin Ali Raza Anjum, Mohammad Rizwan Khan, Naveed Kausar Janjua
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: Coatings
• Subjects: CuO/γ-Al₂O₃; ammonia electro-oxidation (AEO); electrochemical surface area (ECSA); electrocatalysts
• Online Access: https://www.mdpi.com/2079-6412/11/3/313

Ammonia electro-oxidation (AEO) is a zero carbon-emitting sustainable means for the generation of hydrogen fuel, but its commercialization is deterred due to sluggish reaction kinetics and the poisoning of expensive metal electrocatalysts. With this perspective, CuO impregnated γ-Al₂O₃ (CuO/γ-Al₂O₃) hybrid materials were synthesized as effective and affordable electrocatalysts and investigated for AEO in alkaline media. Structural investigations were performed via different characterization techniques, i.e., X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical impedance spectroscopy (EIS). The morphology of γ-Al₂O₃ support as interconnected porous structures rendered the CuO/γ-Al₂O₃ nanocatalysts with robust activity. The additional CuO impregnation resulted in the enhanced electrochemical active surface area (ECSAs) and diffusion coefficient and spiked the electrocatalytic performance for NH₃ electrolysis. Owing to good values of diffusion coefficient for AEO, low bandgap, and availability of ample ECSA at higher CuO to γ-Al₂O₃ ratio, these proposed electrocatalysts were proved to be effective in AEO. Due to good reproducibility, electrochemical stability, and higher activity for ammonia electro-oxidation, CuO/γ-Al₂O₃ nanomaterials are proposed as efficient promoters, electrode materials, or catalysts in ammonia electrocatalysis.