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

Abstract

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.