Coverages and Configurations of CO* and H* on Pt(111) under Realistic Reaction Conditions
5 affiliations
- 1William G. Lowrie Department of Chemical & Biomolecular Engineering, Ohio State University, 151 W. Woodruff Rd., Columbus, Ohio, 43210
- 2Center for Programmable Energy Catalysis
- 3Minnesota
- 4Department of Chemical Engineering
- 5University of California Santa Barbara
Abstract
Lateral interactions between co–adsorbed species can produce non-random spatial organization that governs the availability of reactive motifs relevant to catalytic behavior. For CO* and H* co–adsorbed on Pt(111), these interactions determine how the two species distribute across the surface and therefore which local CO*–H* configurations are available under reaction conditions. In this work, we combine density functional theory, cluster expansions, and grand canonical Monte Carlo simulations to determine how CO* and H* organize on Pt(111), and subsequently use electronic surface charge as a controlled perturbation to examine how this organization responds to changes in the underlying energetics. On neutral Pt(111), CO*–H* first-nearest-neighbor interactions are strongly repulsive (0.42 eV), CO*–CO* first-nearest-neighbor interactions are moderately repulsive (0.12 eV), and H*–H* interactions are comparatively weak. These interactions cause CO* to nucleate into islands that grow and coalesce with increasing CO* coverage, while H* preferentially occupies regions outside CO*-rich domains. Consequently, the abundance of CO*–H* nearest-neighbor configurations varies non-monotonically with CO* coverage, reaching a maximum at intermediate coverage before decreasing as CO* islands grow and the adsorbates become increasingly segregated. Positive surface charge strengthens CO* adsorption but also increases CO*–CO* repulsion, producing higher CO* coverages, a broader distribution of CO* island sizes, and larger low-coverage regions between islands where H* can adsorb away from CO*. This suppresses CO*–H* nearest-neighbor configurations relative to the neutral surface. Negative charging weakens CO* adsorption, producing lower CO* coverages, higher H* coverages, and less consolidated CO* islands, thereby increasing the prevalence of mixed CO*–H* local environments. At intermediate CO* coverage, CO* islands enter a regime of accelerated growth and coalescence that coincides with a shallow plateau in H* coverage. This coincidence suggests that the onset of CO* island coalescence is accompanied by a reorganization of the co-adsorbed layer. Further, it illustrates the strong influence of lateral interactions on the formation of potentially reactive motifs, highlighting how they become influential in determining catalytic reactivity.
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BibTeX
@misc{hossain2026coverages,
title = {{Coverages and Configurations of CO* and H* on Pt(111) under Realistic Reaction Conditions}},
author = {Sifat Hossain and Venkata Rohit Punyapu and Phillip Christopher and Rachel B. Getman},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15009043/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009043/v1},
note = {CC BY-NC},
}
RIS
TY - UNPB
TI - Coverages and Configurations of CO* and H* on Pt(111) under Realistic Reaction Conditions
AU - Sifat Hossain
AU - Venkata Rohit Punyapu
AU - Phillip Christopher
AU - Rachel B. Getman
PY - 2026
DA - 2026/09/18
PB - ChemRxiv
DO - 10.26434/chemrxiv.15009043/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009043/v1
AB - Lateral interactions between co–adsorbed species can produce non-random spatial organization that governs the availability of reactive motifs relevant to catalytic behavior. For CO* and H* co–adsorbed on Pt(111), these interactions determine how the two species distribute across the surface and therefore which local CO*–H* configurations are available under reaction conditions. In this work, we combine density functional theory, cluster expansions, and grand canonical Monte Carlo simulations to determine how CO* and H* organize on Pt(111), and subsequently use electronic surface charge as a controlled perturbation to examine how this organization responds to changes in the underlying energetics. On neutral Pt(111), CO*–H* first-nearest-neighbor interactions are strongly repulsive (0.42 eV), CO*–CO* first-nearest-neighbor interactions are moderately repulsive (0.12 eV), and H*–H* interactions are comparatively weak. These interactions cause CO* to nucleate into islands that grow and coalesce with increasing CO* coverage, while H* preferentially occupies regions outside CO*-rich domains. Consequently, the abundance of CO*–H* nearest-neighbor configurations varies non-monotonically with CO* coverage, reaching a maximum at intermediate coverage before decreasing as CO* islands grow and the adsorbates become increasingly segregated. Positive surface charge strengthens CO* adsorption but also increases CO*–CO* repulsion, producing higher CO* coverages, a broader distribution of CO* island sizes, and larger low-coverage regions between islands where H* can adsorb away from CO*. This suppresses CO*–H* nearest-neighbor configurations relative to the neutral surface. Negative charging weakens CO* adsorption, producing lower CO* coverages, higher H* coverages, and less consolidated CO* islands, thereby increasing the prevalence of mixed CO*–H* local environments. At intermediate CO* coverage, CO* islands enter a regime of accelerated growth and coalescence that coincides with a shallow plateau in H* coverage. This coincidence suggests that the onset of CO* island coalescence is accompanied by a reorganization of the co-adsorbed layer. Further, it illustrates the strong influence of lateral interactions on the formation of potentially reactive motifs, highlighting how they become influential in determining catalytic reactivity.
ER -