Synthesis of alloyed PtPd nanowires and study on their electro-catalytic performance to methanol oxidation reaction

Abstract

Alloying Pt with foreign metal to modulate the electronic structure and controlling the geometric morphology of Pt nanomaterials to tailor the surface structure are two extensively applied strategies to promote the electrocatalytic activity of Pt nanomaterials in fuel cell reactions. The former enhances the intrinsic catalytic activity of the nano-catalysts while the latter increases the number of active sites for catalytic reactions. So why not combine the two strategies to construct highly efficient Pt-based nano-catalysts? Within this work, we successfully synthesized one-dimensional PtPd nanowires through a one-pot method by exploiting the similarities of Pt and Pd, like identical lattice constants. The as-prepared products had alloyed structures and ultrafine profiles of nanowires. The electrochemical test indicated that the PtPd nanowires as-prepared possessed superior catalytic activity to methanol oxidation reaction with the mass activity of 2071 mAmg−1, significantly better than that of the commercial Pt/C (473 mAmg−1). Density functional theory calculation showed that with the introduction of Pd, the d-band electron center of Pt would downshift and the adsorbed interaction between CO intermediates (CO∗) with the surface of catalysts would diminish, which would improve the resistance of the catalysts to the toxicity of CO∗, thus enhancing the electro-catalytic activity and stability. Apart from the alloying effect, the unique structure of the one-dimensional ultra-fine nanowires could guarantee adequate atoms would be involved to expose and provide sufficient active sites for reactions, which was another essential factor in the promotion of the electro-catalytic performance.