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SUMMARY:Pt steps control H2 and O2 surface reactions in various ways
DTSTART:20190416T171500
DTEND:20190416T181500
DTSTAMP:20260510T053515Z
UID:9ddd6a929a0635c4ac7c7e53faaccbe54cda64d7c3fc3d4fddec8dd6
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Ludo B.F. Juurlink\nUniversiteit Leiden \nThe Netherland
 s\nCollisions of H2 and O2 molecules with Pt surfaces are relevant to actu
 al heterogeneous (electro)catalysis. They also serve as model systems to d
 evelop improved theoretical methods to predicting chemical reaction dynami
 cs and kinetics. We use Pt step type and step density variations to study 
 how common defects on catalytic particles affects H2 and O2 sticking and d
 issociation. In Leiden\, we use a curved surface approach. The curved surf
 ace of Pt single crystals yields a continuous variation in step density wi
 th spatial separation of step types. In combination with supersonic molecu
 lar beam techniques we unveil how the local corrugation of monoatomic step
 s controls single collision events. For H2\, our studies resolved a 40-yea
 r old debate on the origin of defects dominating dissociation1. The predom
 inant dissociation mechanisms are direct and elementary. Various dependenc
 ies of reactivity are inconsistent with a physisorbed\, precursor-based mo
 del for H2 dissociation. For O2\, the opposite is true. Here\, a physisorb
 ed state is crucial to molecular sticking and subsequent reactions at low 
 collision energies.  At higher energies\, the physisorbed state loses imp
 ortance and direct adsorption into molecular chemisorbed states dominate r
 eactivity. The latter conclusions required complementary experiments perfo
 rmed with dr. Kurahashi in Tsukuba\, Japan. We used spin-rotation state-se
 lected and aligned O2 to determine how rotation parallel and perpendicular
  to the Pt(111) plane and the A- and B-type step direction affect trapping
  and dissociation on various ‘flat’ Pt single crystals.\n 
LOCATION:CH G1 495 https://plan.epfl.ch/?room==CH%20G1%20495
STATUS:CONFIRMED
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