Electrochemical deposition of PtRu on an uncatalyzed carbon electrode for methanol electrooxidation

This research aims to increase the utilization of platinum–ruthenium alloy (PtRu) catalysts and thus to lower the catalyst loadings in the electrode for methanol electrooxidation. The electrodeposition of PtRu was performed on a rotating disk electrode (RDE) of glassy carbon (GC), on which a layer of Nafion®-bonded carbon (Vulcan XC 72R) was dispersed in advance. First, the behavior of Pt RDE and GC RDE in an aqueous solution containing HCl, H2PtCl6 and RuCl3 was studied. It was found that the hydrogen evolution becomes a dominant reaction when the electrode potential is below −0.20 V vs. SSCE (saturated-potassium–chloride silver chloride electrode). The hydrogen evolution was strongly enhanced with the formation of nanometer-sized Pt particles on the RDE. To enrich Pt and Ru ions, present in the form of anionic complexes in solution, onto the carbon particles in the uncatalyzed carbon electrode (UCE) and, most importantly, to eliminate the hydrogen bubbles formed on the UCE during the cathodic deposition, a positive current was imposed on the UCE for a period of time prior to each step of cathodic deposition of PtRu, should multiple steps of cathodic deposition be required. Cyclic voltammograms (CVs) of electrodes in 0.5 M H2SO4 before and after deposition were used to evaluate the loading of metal catalysts based upon the profile of CV in a wide range of potentials from −0.20 to 1.1 V vs. SSCE. The catalytic activity of electrodes prepared under different conditions for methanol electrooxidation was studied by electrochemical methods. The results showed that the performance of the electrode (prepared in this study) with loadings estimated to 77 μg PtRu/cm2 is much better than that of a conventional electrode with loadings of 100 μg Pt/cm2. The role of ruthenium in methanol oxidation was also discussed in electrochemical terms.

[1]  A. Dickinson.  Preparation of a Pt$z.sbnd;Ru/C catalyst from carbonyl complexes for fuel cell applications , 2002 .

[2]  Makoto Uchida,et al.  Effects of Microstructure of Carbon Support in the Catalyst Layer on the Performance of Polymer‐Electrolyte Fuel Cells , 1996 .

[3]  John Davey,et al.  Recent advances in direct methanol fuel cells at Los Alamos National Laboratory , 2000 .

[4]  J. Tan,et al.  Diagnosis of specific surface area in fuel cell air electrodes , 2001 .

[5]  G. Squadrito,et al.  Influence of the structure in low-Pt loading electrodes for polymer electrolyte fuel cells , 1998 .

[6]  Supramaniam Srinivasan,et al.  High performance proton exchange membrane fuel cells with sputter-deposited Pt layer electrodes , 1997 .

[7]  Timothy C. Stoner,et al.  Increasing Proton Exchange Membrane Fuel Cell Catalyst Effectiveness Through Sputter Deposition , 2002 .

[8]  H. Gasteiger,et al.  Electro-oxidation mechanisms of methanol and formic acid on Pt-Ru alloy surfaces , 1995 .

[9]  M. Forsyth,et al.  Platinum electrodeposition for polymer electrolyte membrane fuel cells , 2001 .

[10]  K. Choi,et al.  Electrode fabrication for proton exchange membrane fuel cells by pulse electrodeposition , 1998 .

[11]  J. Song,et al.  Optimal composition of polymer electrolyte fuel cell electrodes determined by the AC impedance method , 2001 .

[12]  I. Uchida,et al.  Porous-microelectrode study on Pt/C catalysts for methanol electrooxidation , 2003 .

[13]  E. J. Taylor,et al.  Preparation of High‐Platinum‐Utilization Gas Diffusion Electrodes for Proton‐Exchange‐Membrane Fuel Cells , 1992 .

[14]  D. Zhou,et al.  Electrochemical characterisation of oxygen reduction on teflon-bonded gas diffusion electrodes , 1995 .

[15]  Edson A. Ticianelli,et al.  Recent advances in solid polymer electrolyte fuel cell technology with low platinum loading electrodes , 1990 .

[16]  V. Antonucci,et al.  Optimization of operating parameters of a direct methanol fuel cell and physico-chemical investigation of catalyst–electrolyte interface , 1998 .

[17]  C. Lamy,et al.  Electrocatalytic oxidation of methanol on platinum nanoparticles electrodeposited onto porous carbon substrates , 1997 .

[18]  S. Wasmus,et al.  Methanol oxidation and direct methanol fuel cells: a selective review 1 In honour of Professor W. Vi , 1999 .

[19]  S. Narayanan,et al.  Performance of Direct Methanol Fuel Cells with Sputter‐Deposited Anode Catalyst Layers , 1999 .