Synthesis, physical characterization, and electrochemical evaluation of bimetallic PtNi nanoparticles supported on different pristine carbon materials to evaluate the effect of supports in catalytic activity toward the oxygen reduction to PEM fuel cells

Abstract

The following doctoral thesis work presents a series of studies to address the synthesis, physical characterization and electrochemical evaluation of polyhedral PtNi catalysts supported on different carbon materials for the oxygen reduction reaction (ORR).The main objective of this study is to evaluate the effect on the catalytic activity of pristine carbon supports used in polyhedral PtNi catalysts obtained from a versatile chemical synthesis. In addition, the physicochemical characterization and the electrochemical evaluation of the obtained catalysts were carried out, which is presented through the development of the different stages of this study in the chapters of this investigation. The PtNi nanoparticles were synthesized by a thermochemical reduction route using the hot injection technique of metal precursors using Oleylamine (Oam as reaction agent and shape controller). The synthesis methodology was optimized based on the results obtained where the effect of some of the variables such as temperature, reaction time, and other important factors in the synthesis to obtain our catalysts was observed. As previously mentioned, the carbon supports used in this study were made in their pristine form, that is, they were not subjected to any type of functionalization or surface modification, since generally this type of material on which the catalytic materials are dispersed, are modified by some type of functionalization to improve the dispersion of metallic nanoparticles and favor catalytic activity towards ORR The electrochemical evaluation of the obtained catalysts was carried out to determine their catalytic activity parameters towards the ORR and to determine the effect of the support material on the catalytic activity of our synthesized catalysts. This work is based on the results of different characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy discrimination spectroscopy (EDS) and scanning transmission electron microscopy (STEM). ) and electrochemical evaluations by cyclic voltammetry, CO-stripping and rotating disk electrode. In addition, the experimental observations that can serve as a contribution in the development of future works were made.