Synthesis of Pt@Ni Core-Shell Nanoparticles Using Mwcnt's Supported for Oxygen Reduction Reaction

Abstract

Multi-walled carbon nanotubes (MWCNTs) are nanostructures with unique physicochemical properties. MWCNTs can be obtained using different catalytic agents, being the most common the organometallic materials based on Fe. In this work, MWCNTs were produced using thermal chemical vapor deposition; MWCNTs surface was modified by nitric acid to introduce functional groups which act as anchors for metallic nanoparticles. On the other hand, the oxygen reduction reaction (ORR) in a tends to be the slowest reaction in a fuel cells, being this important issue to solve. It has been demonstrated that bimetallic catalysts (e.g. PtRu, PtCo, PtNi, etc.) are a good option for the ORR. The effect of the second metal helps the Pt, generating an improvement in the activity. Pt@Ni core-shell nanoparticles with different Pt/Ni ratios have been prepared by chemical reduction, supported onto MWCNTs and used as electrocatalysts for PEMFC. Chemical reduction allows the production of a very narrow size distribution of metal particles, with an average size around the 10 nm. The morphology of the electrocatalyst was characterized by XRD and HRTEM. It was found that the Pt@NiMWCNTs catalyst exhibited a core-shell nanostructure. The ORR on Pt@Ni core shell was studied using the rotating disk electrode (RDE) technique in an O 2 -saturated acid solution. A normal three electrode cell was used with the Pt@Ni/MWCNT as working electrode (deposited in glassy carbon), Ag/AgCl (KCl Sat) as reference, a Pt wire as counter electrode, and 0.5M H 2 SO 4 as electrolyte. The results and discussion of the electrochemical studies will be discussed.