Evidence of nonelectrochemical shift reaction on a CO-tolerant high-entropy state Pt-Ru anode catalyst for reliable and efficient residential fuel cell systems.

A randomly mixed monodispersed nanosized Pt-Ru catalyst, an ultimate catalyst for CO oxidation reaction, was prepared by the rapid quenching method. The mechanism of CO oxidation reaction on the Pt-Ru anode catalyst was elucidated by investigating the relation between the rate of CO oxidation reaction and the current density. The rate of CO oxidation reaction increased with an increase in unoccupied sites kinetically formed by hydrogen oxidation reaction, and the rate was independent of anode potential. Results of extended X-ray absorption fine structure spectroscopy showed the combination of N(Pt-Ru)/(N(Pt-Ru) + N(Pt-Pt)) ≑ M(Ru)/(M(Pt) + M(Ru)) and N(Ru-Pt)/(N(Ru-Pt) + N(Ru-Ru)) ≑ M(Pt)/(M(Ru) + M(Pt)), where N(Pt-Ru)(N(Ru-Pt)), N(Pt-Pt)(N(Ru-Ru)), M(Pt), and M(Ru) are the coordination numbers from Pt(Ru) to Ru(Pt) and Pt (Ru) to Pt (Ru) and the molar ratios of Pt and Ru, respectively. This indicates that Pt and Ru were mixed with a completely random distribution. A high-entropy state of dispersion of Pt and Ru could be maintained by rapid quenching from a high temperature. It is concluded that a nonelectrochemical shift reaction on a randomly mixed Pt-Ru catalyst is important to enhance the efficiency of residential fuel cell systems under operation conditions.

[1]  G. Henkelman,et al.  Mechanism for the water–gas shift reaction on monofunctional platinum and cause of catalyst deactivation , 2011 .

[2]  S. Seino,et al.  Methanol oxidation catalysis and substructure of PtRu/C bimetallic nanoparticles synthesized by a radiolytic process , 2011 .

[3]  Guoxiong Wang,et al.  Particle size dependence of CO tolerance of anode PtRu catalysts for polymer electrolyte fuel cells , 2010 .

[4]  Guoxiong Wang,et al.  A Comparative Study of Variously Prepared Carbon-Supported Pt / MoO x Anode Catalysts for a Polymer Electrolyte Fuel Cell , 2009 .

[5]  H. Okamoto.  Pt-Ru (Platinum-Ruthenium) , 2008 .

[6]  Steven T. Evans,et al.  Mechanism of the Water Gas Shift Reaction on Pt: First Principles, Experiments, and Microkinetic Modeling , 2008 .

[7]  K. Seshan,et al.  Bifunctional catalysts for single-stage water-gas shift reaction in fuel cell applications. Part 1. Effect of the support on the reaction sequence. , 2007 .

[8]  Hideo Daimon,et al.  Methanol oxidation catalysis and substructure of PtRu bimetallic nanoparticles , 2007 .

[9]  S. Hasegawa,et al.  Mechanistic study of water–gas-shift reaction over TiO2 supported Pt–Re and Pd–Re catalysts , 2005 .

[10]  C. Roth,et al.  Determination of O[H] and CO coverage and adsorption sites on PtRu electrodes in an operating PEM fuel cell. , 2005, Journal of the American Chemical Society.

[11]  A. Wiȩckowski,et al.  Ru-decorated Pt surfaces as model fuel cell electrocatalysts for CO electrooxidation. , 2005, The journal of physical chemistry. B.

[12]  S. Haq,et al.  Intact and dissociative adsorption of water on Ru(0 0 0 1) , 2004 .

[13]  Ermete Antolini,et al.  Formation of carbon-supported PtM alloys for low temperature fuel cells: a review , 2003 .

[14]  K. Asakura,et al.  Extended X-ray Absorption Fine Structure Studies on the Structure of the Poly(vinylpyrrolidone)-Stabilized Cu/Pd Nanoclusters Colloidally Dispersed in Solution , 2002 .

[15]  E. Passalacqua,et al.  Physical and morphological characteristics and electrochemical behaviour in PEM fuel cells of PtRu /C catalysts , 2001 .

[16]  V. Idakiev,et al.  Low-temperature water-gas shift reaction on Auα-Fe2O3 catalyst , 1996 .

[17]  H. Gasteiger,et al.  H2 and CO Electrooxidation on Well-Characterized Pt, Ru, and Pt-Ru. 1. Rotating Disk Electrode Studies of the Pure Gases Including Temperature Effects , 1995 .

[18]  T. Shido,et al.  Reactant-Promoted Reaction Mechanism for Water-Gas Shift Reaction on Rh-Doped CeO2 , 1993 .

[19]  T. Shido,et al.  Regulation of reaction intermediate by reactant in the water-gas shift reaction on CeO2, in relation to reactant-promoted mechanism , 1992 .

[20]  A. Aldaz,et al.  Electrochemical studies in sulphuric acid solutions of adsorbed CO on Pt (111) electrodes , 1990 .

[21]  P. Thiel,et al.  Adsorption of water on Ru(100) , 1989 .

[22]  C. Campbell,et al.  A surface science investigation of the water-gas shift reaction on Cu(111) , 1987 .

[23]  M. Watanabe,et al.  Electrocatalysis by ad-atoms: Part III. Enhancement of the oxidation of carbon monoxide on platinum by ruthenium ad-atoms , 1975 .

[24]  Masahiro Watanabe,et al.  Electrocatalysis by ad-atoms: Part II. Enhancement of the oxidation of methanol on platinum by ruthenium ad-atoms , 1975 .