Journal ArticleDOI
Effect of surface composition on electronic structure, stability, and electrocatalytic properties of Pt-transition metal alloys: Pt-skin versus Pt-skeleton surfaces.
Vojislav R. Stamenkovic,Bongjin Simon Mun,Karl Johann Jakob Mayrhofer,Philip N. Ross,Nenad M. Markovic +4 more
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TLDR
These three different near-surface compositions (Pt-skin, Pt-skeleton, and pure polycrystalline Pt) all having pure-Pt outermost layers are found to have different electronic structures, which originates from different arrangements of subsurface atoms of the alloying component.Abstract:
The surface properties of PtM (M = Co, Ni, Fe) polycrystalline alloys are studied by utilizing Auger electron spectroscopy, low energy ion scattering spectroscopy, and ultraviolet photoemission spectroscopy. For each alloy initial surface characterization was done in an ultrahigh vacuum (UHV) system, and depending on preparation procedure it was possible to form surfaces with two different compositions. Due to surface segregation thermodynamics, annealed alloy surfaces form the outermost Pt-skin surface layer, which consists only platinum atoms, while the sputtered surfaces have the bulk ratio of alloying components. The measured valence band density of state spectra clearly shows the differences in electronic structures between Pt-skin and sputtered surfaces. Well-defined surfaces were hereafter transferred out from UHV and exposed to the acidic (electro)chemical environment. The electrochemical and post-electrochemical UHV surface characterizations revealed that Pt-skin surfaces are stable during and af...read more
Citations
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Journal ArticleDOI
Electrocatalyst approaches and challenges for automotive fuel cells
TL;DR: Taking the step towards successful commercialization requires oxygen reduction electrocatalysts that meet exacting performance targets, and these catalyst systems will need to be highly durable, fault-tolerant and amenable to high-volume production with high yields and exceptional quality.
Journal ArticleDOI
Design of electrocatalysts for oxygen- and hydrogen-involving energy conversion reactions
TL;DR: The emphasis of this review is on the origin of the electrocatalytic activity of nanostructured catalysts toward a series of key clean energy conversion reactions by correlating the apparent electrode performance with their intrinsic electrochemical properties.
Journal ArticleDOI
Improved Oxygen Reduction Activity on Pt3Ni(111) via Increased Surface Site Availability
Vojislav R. Stamenkovic,Vojislav R. Stamenkovic,Ben Fowler,Bongjin Simon Mun,Guofeng Wang,Philip N. Ross,Chris Lucas,Nenad M. Markovic +7 more
TL;DR: It is demonstrated that the Pt3Ni( 111) surface is 10-fold more active for the ORR than the corresponding Pt(111) surface and 90-foldMore active than the current state-of-the-art Pt/C catalysts for PEMFC.
Journal ArticleDOI
Recent Advances in Electrocatalysts for Oxygen Reduction Reaction
TL;DR: This comprehensive Review focuses on the low- and non-platinum electrocatalysts including advanced platinum alloys, core-shell structures, palladium-based catalysts, metal oxides and chalcogenides, carbon-based non-noble metal catalysts and metal-free catalysts.
Journal ArticleDOI
Alloys of platinum and early transition metals as oxygen reduction electrocatalysts
Jeffrey Greeley,Ifan E. L. Stephens,Alexander S. Bondarenko,Tobias Peter Johansson,Heine Anton Hansen,Thomas F. Jaramillo,Thomas F. Jaramillo,Jan Rossmeisl,Ib Chorkendorff,Jens K. Nørskov +9 more
TL;DR: A new set of ORR electrocatalysts consisting of Pd or Pt alloyed with early transition metals such as Sc or Y, identified using density functional theory calculations as being the most stable Pt- and Pd-based binary alloys with ORR activity likely to be better than Pt.
References
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Journal ArticleDOI
Origin of the Overpotential for Oxygen Reduction at a Fuel-Cell Cathode
Jens K. Nørskov,Jan Rossmeisl,and Ashildur Logadottir,L. Lindqvist,John R. Kitchin,Thomas Bligaard,Hannes Jónsson +6 more
TL;DR: In this paper, the stability of reaction intermediates of electrochemical processes on the basis of electronic structure calculations was analyzed and a detailed description of the free energy landscape of the electrochemical oxygen reduction reaction over Pt(111) as a function of applied bias was presented.
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Activity benchmarks and requirements for Pt, Pt-alloy, and non-Pt oxygen reduction catalysts for PEMFCs
TL;DR: In this article, the authors quantified the activities and voltage loss modes for state-of-the-art MEAs (membrane electrode assemblies), specifies performance goals needed for automotive application, and provides benchmark oxygen reduction activities for state of the art platinum electrocatalysts.
Journal ArticleDOI
Surface science studies of model fuel cell electrocatalysts
Nenad M. Markovic,Philip N. Ross +1 more
TL;DR: In this paper, the authors discuss progress in the understanding of electrocatalytic reactions through the study of model systems with surface spectroscopies and discuss the limitations of using pure metal single crystals and well-characterized bulk alloys as models for real catalysts.
Journal ArticleDOI
Modification of the surface electronic and chemical properties of Pt(111) by subsurface 3d transition metals
TL;DR: The surfaces investigated in this study had no lateral strain in them, demonstrating that strain is not a necessary factor in the modification of bimetallic surface properties.
Journal ArticleDOI
Electronic structure and catalysis on metal surfaces
TL;DR: First principles calculations are discussed, which can aid in the establishment of chemisorption trends across the transition metals, in the characterization of reaction pathways on individual metals, and in the design of novel catalysts.