Tailored Au and Pt Containing Multi-metallic Nanocomposites for a Promising Fuel Cell Reaction

Abstract

The development of an efficient syntheses method to produce multimetallic nanocomposites with an appropriate structure is required to study the structure–composition–property relationship of the synthesized nanocomposites and to investigate, evaluate their possible technological applications. In this work, a fine hetero-structured Au and Pt containing multi-metallic nanocomposites (Au/Pt/Ag and Au/Pd/Pt colloidal nanocomposites) were synthesized through a microwave irradiation method with the use of trisodium citrate as a reducing agent and it has been coated on the glassy carbon electrode. It is characterized by high-resolution transmission electron microscopy, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopic techniques to elucidate structure, surface morphology, bulk-composition and metallic state of the resulting Au/Pt/Ag and Au/Pd/Pt colloidal nanocomposites respectively. The colloidal nanocomposites were also characterized by zeta potential and dynamic light scattering studies. The electrochemical techniques (cyclic voltammetry and chronoamperometry) have been employed to investigate the electrochemical parameters related to the electro-oxidation of methanol which in turn will be useful for conventional fuel cell applications. In addition to that, the density functional theoretical optimized minimum-energy structures of Pt n (n = 3–6) were studied as they are forming shell and thus involved in catalysis. Electronic density of state plots of the optimized Pt n and Pd n clusters using B3LYP/Lanl2DZ level of theory was made. The multi-metallic nanocomposites of these metals are proposed as a promising new class of catalyst for the electro-oxidation reaction of methanol particularly in fuel-cell applications. The formation of hetero-structure is discussed as the desirable condition to obtain a better electrocatalytic activity. It is also found that, the electrocatalytic activity and stability of the resultant Au/Pt/Ag colloidal nanocomposites modified glassy carbon electrode is much better catalyst towards methanol electrooxidation in acid medium.