Facile Aqueous-Phase Synthesis of the PtAu/Bi₂O₃ Hybrid Catalyst for Efficient Electro-Oxidation of Ethanol

In this work, we present a facile aqueous-phase synthesis of a hybrid catalyst consisting of PtAu alloy supported on Bi₂O₃ microspheres. Multistep reduction of HAuCl₄ and K₂PtCl₄ salts on Bi₂O₃ and subsequent annealing lead to the formation of this hybrid catalyst. To the best of our knowledge, this is the first report of using Bi₂O₃ as a catalyst support in fuel cell applications. The material was characterized by powder X-ray diffraction and various microscopic techniques. This composite showed remarkable activity as well as stability toward the electro-oxidation of ethanol in comparison to commercially available Pt/C. The order of the reactivity was found to be commercial Pt/C (50.4 mA/m²mg_Pt^-1) < Pt/Bi₂O₃(10) (108 mA/m²mg_Pt^-1) < PtAu/Bi₂O₃(10) (459 mA/m²mg_Pt^-1). The enhancement in the activity can be explained through cooperative effects, namely, ligand effects of gold and Bi₂O₃ support, which helps in removing carbon monoxide molecules to avoid the poisoning of the Pt active sites.