Synthesis and Electrochemical Evaluation of Pd8Sb3 and PtSb Ordered Intermetallics Toward the Oxygen Reduction and Hydrogen Oxidation Reactions
Alghamdi, Hamdan A
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Energy consumption and chemical conversion from nonrenewable sources such as fossil fuels greatly affect the environment and it is a leading global issue. Electrochemical conversion once mature could pose as an alternative technology, yet, electrode materials require further development to increase efficiencies and reduce cost. While precious metals exhibit high activities and stability as electrocatalyst, their cost and the possibility of activity enhancement led many to finding alternative materials. Alloying precious metals with non-precious metals to reduce the amount of precious metals used and hence total cost has also shown to increase activities in some cases. In this work, two ordered intermetallics of Pd8Sb3 and PtSb are synthesized and evaluated toward oxygen reduction and hydrogen oxidation reactions, respectively. Single phase Pd8Sb3 ordered intermetallic supported on carbon is successfully synthesized at a low temperature of 250°C. The electrochemical oxygen reduction activity of as-synthesized Pd8Sb3 in alkaline conditions closely matches Pd efficiency with ~ 1 mA/cm2. The activity of Pd8Sb3, however, is improved to 1.65 mA/cm2 upon annealing to 500°C. Additionally, dominant single phase PtSb/C electrocatalyst is synthesized and its efficiency towards the hydrogen oxidation reaction in alkaline conditions is evaluated. PtSb exhibits better specific activity for the reaction with kinetic currents of 13 and 4 mA/cm2 at 100 and 10 V.