Chemphyschem : a European journal of chemical physics and physical chemistry, Jan 6, 2015
Platinum is a catalyst of choice in scientific investigations and technological applications, whi... more Platinum is a catalyst of choice in scientific investigations and technological applications, which are both often carried out in the presence of oxygen. Thus, a fundamental understanding of platinum's (electro)catalytic behavior requires a detailed knowledge of the structure and degree of oxidation of platinum surfaces in operando. ReaxFF reactive force field calculations of the surface energies for structures with up to one monolayer of oxygen on Pt(111) reveal four stable surface phases characterized by pure adsorbate, high- and low-coverage buckled, and subsurface-oxygen structures, respectively. These structures and temperature programmed desorption (TPD) spectra simulated from them compare favorably with and complement published scanning tunneling microscopy (STM) and TPD experiments. The surface buckling and subsurface oxygen observed here influence the surface oxidation process, and are expected to impact the (electro)catalytic properties of partially oxidized Pt(111) su...
ABSTRACT Abstract A microkinetic model of the oxygen reduction reaction (ORR) on Pt(111) under a ... more ABSTRACT Abstract A microkinetic model of the oxygen reduction reaction (ORR) on Pt(111) under a gaseous \(\hbox {H}_2\) and \(\hbox {O}_2\) atmosphere is used to predict and explain which compositions of \(\hbox {H}_2\) and \(\hbox {O}_2\) lead to the fastest rate of water formation for temperatures between 600 and 900 K. For a stoichiometric (2:1) mixture of \(\hbox {H}_2\) and \(\hbox {O}_2\) the rate-determing step is found to transition from \(\hbox {O}^\star\) hydrogenation to \(\hbox {O}{_2}{^\star }\) dissociation over this same temperature range. These results are explained in terms of the temperature dependence of the surface coverages of \(\hbox {O}^\star\) and \(\hbox {H}^\star\) and are shown to be consistent with kinetic models aimed at understanding the ORR under electrochemical conditions. Graphical Abstract .
Physical chemistry chemical physics : PCCP, Jan 14, 2014
ReaxFF force field parameters describing Pt-Pt and Pt-O interactions have been developed and test... more ReaxFF force field parameters describing Pt-Pt and Pt-O interactions have been developed and tested. The Pt-Pt parameters are shown to accurately account for the chemical nature, atomic structures and other materials properties of bulk platinum phases, low and high-index platinum surfaces and nanoclusters. The Pt-O parameters reliably describe bulk platinum oxides, as well as oxygen adsorption and oxide formation on Pt(111) terraces and the {111} and {100} steps connecting them. Good agreement between the force field and both density functional theory (DFT) calculations and experimental observations is demonstrated in the relative surface free energies of high symmetry Pt-O surface phases as a function of the oxygen chemical potential, making ReaxFF an ideal tool for more detailed investigations of more complex Pt-O surface structures. Validation for its application to studies of the kinetics and dynamics of surface oxide formation in the context of either molecular dynamics (MD) or...
ABSTRACT Die synergetische Rolle von koadsorbiertem CO und OH zur Promotierung der HCOOH‐Elektroo... more ABSTRACT Die synergetische Rolle von koadsorbiertem CO und OH zur Promotierung der HCOOH‐Elektrooxidation an Pt(111) wurde untersucht, indem die Details der mechanistischen Reaktionsabläufe mithilfe der Dichtefunktionaltheorie aufgelöst wurden. Anhand abgeleiteter kinetischer Modelle konnten die Oberflächenphänomene entlang der experimentellen Cyclovoltammetriemessungen von 0.0 bis 1.2 V auf atomarer Ebene aufgelöst werden.
Chemphyschem : a European journal of chemical physics and physical chemistry, Jan 6, 2015
Platinum is a catalyst of choice in scientific investigations and technological applications, whi... more Platinum is a catalyst of choice in scientific investigations and technological applications, which are both often carried out in the presence of oxygen. Thus, a fundamental understanding of platinum's (electro)catalytic behavior requires a detailed knowledge of the structure and degree of oxidation of platinum surfaces in operando. ReaxFF reactive force field calculations of the surface energies for structures with up to one monolayer of oxygen on Pt(111) reveal four stable surface phases characterized by pure adsorbate, high- and low-coverage buckled, and subsurface-oxygen structures, respectively. These structures and temperature programmed desorption (TPD) spectra simulated from them compare favorably with and complement published scanning tunneling microscopy (STM) and TPD experiments. The surface buckling and subsurface oxygen observed here influence the surface oxidation process, and are expected to impact the (electro)catalytic properties of partially oxidized Pt(111) su...
ABSTRACT Abstract A microkinetic model of the oxygen reduction reaction (ORR) on Pt(111) under a ... more ABSTRACT Abstract A microkinetic model of the oxygen reduction reaction (ORR) on Pt(111) under a gaseous \(\hbox {H}_2\) and \(\hbox {O}_2\) atmosphere is used to predict and explain which compositions of \(\hbox {H}_2\) and \(\hbox {O}_2\) lead to the fastest rate of water formation for temperatures between 600 and 900 K. For a stoichiometric (2:1) mixture of \(\hbox {H}_2\) and \(\hbox {O}_2\) the rate-determing step is found to transition from \(\hbox {O}^\star\) hydrogenation to \(\hbox {O}{_2}{^\star }\) dissociation over this same temperature range. These results are explained in terms of the temperature dependence of the surface coverages of \(\hbox {O}^\star\) and \(\hbox {H}^\star\) and are shown to be consistent with kinetic models aimed at understanding the ORR under electrochemical conditions. Graphical Abstract .
Physical chemistry chemical physics : PCCP, Jan 14, 2014
ReaxFF force field parameters describing Pt-Pt and Pt-O interactions have been developed and test... more ReaxFF force field parameters describing Pt-Pt and Pt-O interactions have been developed and tested. The Pt-Pt parameters are shown to accurately account for the chemical nature, atomic structures and other materials properties of bulk platinum phases, low and high-index platinum surfaces and nanoclusters. The Pt-O parameters reliably describe bulk platinum oxides, as well as oxygen adsorption and oxide formation on Pt(111) terraces and the {111} and {100} steps connecting them. Good agreement between the force field and both density functional theory (DFT) calculations and experimental observations is demonstrated in the relative surface free energies of high symmetry Pt-O surface phases as a function of the oxygen chemical potential, making ReaxFF an ideal tool for more detailed investigations of more complex Pt-O surface structures. Validation for its application to studies of the kinetics and dynamics of surface oxide formation in the context of either molecular dynamics (MD) or...
ABSTRACT Die synergetische Rolle von koadsorbiertem CO und OH zur Promotierung der HCOOH‐Elektroo... more ABSTRACT Die synergetische Rolle von koadsorbiertem CO und OH zur Promotierung der HCOOH‐Elektrooxidation an Pt(111) wurde untersucht, indem die Details der mechanistischen Reaktionsabläufe mithilfe der Dichtefunktionaltheorie aufgelöst wurden. Anhand abgeleiteter kinetischer Modelle konnten die Oberflächenphänomene entlang der experimentellen Cyclovoltammetriemessungen von 0.0 bis 1.2 V auf atomarer Ebene aufgelöst werden.
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