Hydrogen adsorption and coadsorption with CO on well-defined bimetallic PtRu surfaces––a model study on the CO tolerance of bimetallic PtRu anode catalysts in low temperature polymer electrolyte fuel cells

• Published in: Surface science Vol. 541; no. 1; pp. 137 - 146
• Main Authors: Diemant, T, Hager, T, Hoster, H.E, Rauscher, H, Behm, R.J
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.09.2003; Amsterdam Elsevier Science; New York, NY
• Subjects: Adsorption and desorption kinetics; evaporation and condensation; Adsorption kinetics; Alloys; Carbon monoxide; Condensed matter: structure, mechanical and thermal properties; Deuterium; Exact sciences and technology; Hydrogen molecule; Metallic surfaces; Physics; Platinum; Ruthenium; Scanning tunneling microscopy; Solid-fluid interfaces; Surface electronic phenomena (work function, surface potential, surface states, etc.); Surface stress; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thermal desorption; Metallic surfaces; Surface electronic phenomena (work function, surface potential, surface states, etc.); Deuterium; Scanning tunneling microscopy; Ruthenium; Surface stress; Platinum; Alloys; Hydrogen molecule; Adsorption kinetics; Thermal desorption; Carbon monoxide; Inorganic adsorbate; surface states; etc.); Surface stress; Alloys; Ruthenium; Platinum; Thermal desorption; Scanning tunneling microscopy; Hydrogen molecule; Deuterium; Carbon monoxide; Adsorption energy; Coadsorption; Thermally stimulated desorption; Experimental study; Physisorption; STM; Adsorption kinetics; Metallic surfaces; Surface electronic phenomena (work function; Surface stresses; Gas solid adsorption; Binary alloys; Gas solid interface; Metallic adsorbent; surface potential; Hydrogen molecules
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/S0039-6028(03)00915-4

The influence of PtRu surface alloy formation and of coadsorbed CO on the adsorption/desorption characteristics of hydrogen on bimetallic PtRu surfaces was investigated by temperature programmed desorption, using a 40% Pt containing PtRu surface alloy pseudomorphic on a Ru(0 0 0 1) surface with an almost statistical distribution of Pt surface atoms as substrate. Alloy formation leads to a significant broadening of the desorption peak compared to pure Ru, together with a considerable down-shift in the onset of desorption. This trend is even more pronounced in the presence of coadsorbed CO. The weakening of the hydrogen adsorption bond is attributed mainly to strain effects, imposed by the considerable compression of the pseudomorphic Pt as compared to bulk Pt(1 1 1). Finally we discuss the implications of these results for the mechanistic understanding of the improved performance of PtRu anode catalysts in reformate operated polymer electrolyte fuel cells.