Investigation of the nanostructured electrocatalysts composed by Ag and Pd for BH4- ions electrooxidation in alkaline media

Abstract

Fuel cells powered by borohydride ions (BH4-) are considered attractive energy sources, especially for portable applications. These cells have a high theoretical voltage (1.64 V) and a high number of electrons per ion. However, the lack of a highly efficient electrocatalysts for the borohydride oxidation reaction limits the performance of these devices. It has been observed that, using mainly gold and platinum as electrocatalysts, there is a competition between the total borohydride oxidation reaction (involving 8 electrons) and the hydrolysis reaction, which leads to a smaller number of electrons exchanged per BH4- anion. Therefore, it is desirable the development of electrocatalysts that lead to the direct BH4- oxidation reaction pathway. In view of this, in order to evaluate metals that allow an optimal balance between the opposite tendencies of B-H breaking bond and the oxygen addition, the BH4- adsorption free energies have to be adjusted. The combination between different metals can result in different strengths of BH4- adsorption on the bimetallic surface, conducting, possibly, to a fine-tuning of the two opposite trends of bond breaking and bond formation. Therefore, this project aims to synthesize and study the structural characteristics of nanostructured electrocatalysts composed by the combination of Ag and Pd for the BH4- electrooxidation reaction. The final objective is to advance on the understanding of the bimetallic nanoparticles characteristics that rule the activity for this reaction. (AU)