Pt–Au/C cathode with enhanced oxygen-reduction activity in PEFCs

Abstract

Carbon-supported Pt-Au (Pt-Au/C) catalyst is prepared separately by impregnation, colloidal and micro-emulsion methods, and characterized by physical and electrochemical methods. Highest catalytic activity towards oxygen-reduction reaction (ORR) is exhibited by Pt-Au/C catalyst prepared by colloidal method. The optimum atomic ratio of Pt to Au in Pt-Au/C catalyst prepared by colloidal method is determined using linear-sweep and cyclic voltammetry in conjunction with cell-polarization studies. Among 3:1, 2:1 and 1:1 Pt-Au/C catalysts, (3:1) Pt-Au/C exhibits maximum electrochemical activity towards ORR. Powder X-ray diffraction pattern and transmission electron micrograph suggest Pt-Au alloy nanoparticles to be well dispersed onto the carbon-support. Energy dispersive X-ray analysis and inductively coupled plasma-optical emission spectroscopy data suggest that the atomic ratios of the alloying elements match well with the expected values. A polymer electrolyte fuel cell (PEFC) operating at 0·6 V with (3:1) Pt-Au/C cathode delivers a maximum power-density of 0·65 W/cm 2 in relation to 0·53 W/cm 2 delivered by the PEFC with pristine carbon-supported Pt cathode.

Carbon-Supported Pt-Based Alloy Electrocatalysts for the Oxygen Reduction Reaction in Polymer Electrolyte Membrane Fuel Cells: Particle Size, Shape, and Composition Manipulation and Their Impact to Activity

“…93,94 Typically, colloidal method is a simple Pt-alloy loading method similar to the chemical precipitation method in which with the addition of reducing agent such as NaBH 4 or hydrazine, PtM bimetallic alloyed nanoparticles can be directly reduced and coprecipitated on the carbon support. 95 In a typical colloid experimental procedure of carbon supported Ptalloy, some starting materials such as the metal salt, a reducing agent, and a capping agent have to be mixed while carbon support is added before or after the formation of the Pt-alloy particles. The capping agent can be used to control the size of Pt-alloy particles and thus prevent agglomeration of the particles.…”

“…Currently, there have been some loading methods to prepare Pt-alloy supported on carbon for the PEMFC electrocatalyst application such as chemical precipitation, sol–gel, impregnation, colloidal, microemulsion, polyol method, microwave assisted polyol, electrodeposition, pulse electrodeposition, vapor phase method, sputter deposition technique, cationic exchange, sonochemistry and sonoelectrochemistry, ultrasonic spray pyrolysis, supercritical fluids, high energy ball milling, etc. , Typically, colloidal method is a simple Pt-alloy loading method similar to the chemical precipitation method in which with the addition of reducing agent such as NaBH 4 or hydrazine, PtM bimetallic alloyed nanoparticles can be directly reduced and coprecipitated on the carbon support . In a typical colloid experimental procedure of carbon supported Pt-alloy, some starting materials such as the metal salt, a reducing agent, and a capping agent have to be mixed while carbon support is added before or after the formation of the Pt-alloy particles.…”

Electrochemical Study of Oxygen Reduction on a Carbon‐Supported Core–Shell Platinum–Gold Electrocatalyst with Tuneable Gold Surface Composition

“…However, there is no consensus on the effect of Au on the activity in the ORR. The change in activity upon incorporation of Au is inconsistent in the sense that both a decrease in activity as well as an increase has been reported. We feel that one of the key reasons for such discrepancies might involve the synthetic procedure adopted by the researchers.…”