Electrochemical Investigation of Heat Treated PtRu Nanoparticles Prepared by Modified Polyol Method for Direct Methanol Fuel Cell Application

Abstract

In this work, heat-treated PtRu metal alloys based on multi-walled carbon nanotubes (MWCNT) were synthesized using modified polyol approach for methanol oxidation reaction (MOR) in acidic conditions at 2500, 3500, and 4500 C. The catalysts physical and electrochemical properties were investigated. The High Resolution Transmission Electron Microscopy (HR-TEM) was used to determine the shape, particle size, and particle size distribution of the catalysts, where spherical and agglomerated PtRu nanoparticles with narrow particle size distribution were observed with particle sizes ranging from 0.600 to 1.005 nm. Their crystalline sizes were assessed using the XRD with catalysts presenting a face-centered crystal structure, which is typical of platinum structures with crystalline sizes ranging from 0.500 to 1.180 nm. Energy-Dispersive Spectroscopy, (EDS), was used to identify the elements. Cyclic voltammetry (CV) was used to determine the electroactive surface area (ECSA) and MOR of the electrocatalysts, whereas electrochemical impedance spectrometry (EIS) and chronoamperometry (CA) were used to study their electro-kinetics and stability towards MOR, respectively. PtRu/MWCNT electrocatalysts alloyed at 450°C showed better electroactivity and kinetics as compared to other catalysts, evident from the highest current density of 19.872 mA/cm2 and lowest charge transfer resistance of 0.151 kΩ from CA and EIS, respectively.