Bimetallic Nanocomposites of Palladium (100) and Ruthenium for Electrooxidation of Ammonia

Abstract

Symmmetrically oriented Pd (100) and its bimetallic Pd (100)Ru electrocatalysts were chemically synthesized and their conductive properties employed in the electrochemical oxidation of ammonia. Electrochemical data based on EIS, SWV and CV revealed that the Pt/Pd (100)Ru electrode showed a better conductivity and higher catalytic response towards the electrooxidation of ammonia compared to Pt/Pd (100) electrode. This was demonstrated by the EIS results where Pt/Pd (100)Ru gave a charge transfer resistance (Rct) of 48.64 Ω, high exchange current and lower time constant (5.2738 x 10-1A and 3.2802 x 10-7 s /rad) values while the Pt/Pd (100) had values of 173.2 Ω, 1.4811 x 10-1A and 4.8321 10-7 s /rad. The drastic drop in Rct highlights the superiority of the Pt/Pd (100)Ru over the Pt/Pd (100) and confirms that facile interfacial electron transfer processes occur on the Pt/Pd (100)Ru electrode during the electrocatalytic ammonia oxidation. Investigations through voltammetry revealed that the Pt/Pd (100)Ru had a higher peak current density and a shift in potential to more negative values at ≈ -0.2 V and ≈ -0.4 V. The EASA value of Pt/Pd (100)Ru was found to be 119.24 cm2 whereas Pt/Pd (100) had value of 75.07 cm2. The high electrochemically active surface area of Pd (100)Ru at 119.24 cm2 compared to the 75.07 cm2 for Pd (100) strengthened this observation in performance between the two catalysts for ammonia electrooxidation.

Electrodeposition of Ternary BiTePd Nanofilm Electrocatalyst Using Surface-Limited Reaction for Direct Ethanol Fuel Cell

“…The branches formed grow outwards randomly; Te deposition regulates surface shape by a surface-directed diffusion process, consistent with previous findings. 46 BiTePd showed a flat deposit that was extremely conformal, indicating that the elements were deposited layer by layer. The small white dendritic lumps Te-can be seen, which may be the result of the overpotential deposition step of Te (OPD = −0.550 V).…”

“…The Pd is generally known as one of the best electrocatalysts for EtOH oxidation in alkaline conditions, even in contrast with Pt. [46][47][48] The EOR entails 12 electrons as the following reaction:…”

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

“…This further confirms that CuO species present at the surface of catalysts play important role in AEO, more active sites available at the surface will maximize the ammonia adsorption thus leading to AEO high performance. The AEO strongly depends on the adsorption/desorption of NH 3 species and the number of available active sites of active components at the surface of the electrode [66]. Similarly, two peaks in the cathodic curve are attributed to desorption of ammonia and proton at the surface of the catalysts, Figures 7 and 8 [67].…”

“…Resultantly, 16%-CuO/γ-Al2O3 gives the highest value of the diffusion coefficient as compared to the other materials Ni/Pt [65] and Ni/Ni(OH)2 [18], as enlisted in Table 3. Usually, the diffusion coefficient for AEO in KOH electrolyte (10 −9 ) is much lower than that of water (2.4 × 10 −5 ) [66] due to the presence of hydroxyl (OH − ) ions in the electrolyte [20]. ECSA can be affected by the change of electrode layer structure; thus, 16%-CuO/γ-Al 2 O 3 shows a higher peak current output than 20%-CuO/γ-Al 2 O 3 .…”