Record Details

Stability issues in Pd-based catalysts: the role of surface Pt in improving the stability and oxygen reduction reaction (ORR) activity

DSpace at IIT Bombay

View Archive Info
 
 
Field Value
 
Title Stability issues in Pd-based catalysts: the role of surface Pt in improving the stability and oxygen reduction reaction (ORR) activity
 
Creator SINGH, RK
RAHUL, R
NEERGAT, M
 
Subject RAY-ABSORPTION SPECTROSCOPY
TRANSITION-METAL-ALLOYS
ELECTROCATALYTIC ACTIVITY
THERMODYNAMIC GUIDELINES
BIMETALLIC CATALYSTS
FE NANOPARTICLES
FUEL-CELLS
M-CO
ELECTROREDUCTION
ACID
 
Description Carbon-supported Pd and Pd3Co catalysts have been electrochemically characterized in 0.1 M HClO4 solution and we found that both catalysts were unstable. On repeated potential cycling, the electrochemical surface area of the catalysts decreases and the oxygen reduction reaction (ORR) activity suffers. To stabilize surface Pd atoms of both Pd and Pd3Co catalysts, we deposited Pt using adsorbed hydrogen on the catalytically active Pd sites. The Pt : Pd ratio of Pt-coated Pd and Pt-coated Pd3Co catalysts suggests half-a-monolayer coverage of Pt (two hydrogen atoms required for reducing a Pt2+ ion). The Pt : Pd ratio of Pt-coated Pd3Co catalyst obtained from the simple geometrical hard sphere model, energy-dispersive X-ray spectroscopy (EDS) line scan and bulk EDS agrees very well with that calculated from the hydrogen desorption (H-des) charge of Pd3Co. At the same time, the Pt : Pd ratio of Pt-coated Pd calculated from the H-des charge of Pd catalyst is significantly lower than the ratio obtained from the other methods. Thus, the Pt : Pd ratio of the Pt-coated Pd catalyst estimated from the H-des region of Pd is an underestimation of the composition. This suggests that Pd forms an electrochemically inactive species from the H-upd region itself and Co in Pd3Co seems to stabilize Pd against oxidation by delaying the formation of electrochemically inactive species to higher potentials above the H-upd region. The voltammograms along with the peroxide formation characteristics of the catalysts support the above observations. The deposited Pt on the surface of the Pd and Pd3Co catalysts masks active Pd sites from the electrochemical environment and even partial coverage with Pt improves the stability and ORR activity of the catalysts when compared to that of the respective Pt-free counterparts.
 
Publisher ROYAL SOC CHEMISTRY
 
Date 2014-10-15T07:58:16Z
2014-10-15T07:58:16Z
2013
 
Type Article
 
Identifier PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 15(31)13044-13051
http://dx.doi.org/10.1039/c3cp50697e
http://dspace.library.iitb.ac.in/jspui/handle/100/14624
 
Language en