Following the microscopic pathway to adsorption through chemisorption and physisorption wells

Abstract

Adsorption involves molecules colliding at the surface of a solid and losing their incidence energy by traversing a dynamical pathway to equilibrium. The interactions responsible for energy loss generally include both chemical bond formation (chemisorption) and nonbonding interactions (physisorption). In this work, we present experiments that revealed a quantitative energy landscape and the microscopic pathways underlying a molecule’s equilibration with a surface in a prototypical system: CO adsorption on Au(111). Although the minimum energy state was physisorbed, initial capture of the gas-phase molecule, dosed with an energetic molecular beam, was into a metastable chemisorption state. Subsequent thermal decay of the chemisorbed state led molecules to the physisorption minimum. We found, through detailed balance, that thermal adsorption into both binding states was important at all temperatures.

NO Binding Energies to and Diffusion Barrier on Pd Obtained with Velocity-Resolved Kinetics

“…Approximating hindered rotation as vibration is reasonable for chemisorbed molecules like NO and CO, which have rather high rotational isomerization barriers in their most stable configuration. 26 For the electronic partition function of the adsorbed NO, we use Q ad el = 2 to account for the spin states. The reduction of the electronic partition function for the adsorbate by nearly a factor of 2, compared to the gas phase, is due to the splitting of the doubly degenerate 2π* orbital of NO into a bonding and an antibonding orbital that results from interactions with the metal orbitals.…”

Confining Chainmail‐Bearing Ni Nanoparticles in N‐doped Carbon Nanotubes for Robust and Efficient Electroreduction of CO2

“…Electrochemical CO 2 reduction reaction (CO 2 RR) is a promising and sustainable route to producing CO, which is an important molecule scientifically and industrially [1–6] . Generally, CO 2 is converted into CO via a two‐proton‐two‐electron process, namely, CO 2 +2H + +2e − →CO+H 2 O, E =−0.11 V vs .…”

Chemical dynamics from the gas‐phase to surfaces

“…The design and fruition of extraordinary spectroscopic and molecular beam techniques, coupled with advanced computational modeling, has provided detailed and quantitative knowledge of the dynamics of molecular bond‐breaking and making at surfaces 345 . Recently, detailed balance together with an elaborate microkinetic analysis has been used to show that adsorption to a physisorption well may be facilitated by transient chemisorption in a metastable well with stronger molecule surface interactions 310 …”

“…Naturally, the residence time and the speed distribution of trapping/desorption depends on . Figure 24(e–j) shows vibrational state‐to‐state TOF experiments 310 . Here, CO() is prepared in a molecular beam just 0.5‐mm before collision with a Au(111) surface.…”