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ABSTRACT Rhodium surfaces play a crucial role in heterogeneous catalysis, driving extensive research on their reactivity. In particular, CO oxidation is of great interest, where different oxygen species at the surface can influence catalytic activity. Under certain conditions, rhodium can also host sub‐surface oxygen species, further affecting reaction dynamics. In this work, we combine molecular beam surface scattering, ion imaging, and ultra‐high vacuum techniques to investigate the impact of subsurface oxygen on CO oxidation on single‐crystal Rh surfaces. When oxidizing CO at the (2 1)‐O adlayer without subsurface oxygen, we observe hyperthermal velocity distributions of desorbing CO2, indicating significant energy release along the translational coordinate directly from the transition state. In contrast, subsurface oxygen induces thermal velocity distributions. DFT calculations indicate the formation of a chemisorption state in presence of subsurface oxygen that is energetically favored and transiently traps product CO2long enough for thermalization.
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This content will become publicly available on September 1, 2027
Light-induced molecular functionalization of black phosphorus surfaces with terminal alkenes
Not AvailableThere are few established methods of robust and high-coverage surface functionalization for black phosphorus (BP), effectively limiting the control of its surface reactivity and chemistry. Photochemical grafting of terminal alkenes is known route for the formation of molecular layers on semiconductor surfaces, and here we demonstrate that this chemistry can be applied successfully to BP. We demonstrate that a model alkene 1H-1H-2H-perfluoro-1-decene (PFD) grafts to the surface of BP when illuminated with ultraviolet (UV) light. The reaction self terminates at one molecular monolayer with a surface coverage of approximately 3 molecules/nm2. Control experiments without illumination exhibit only small surface coverages, confirming that the reaction with PFD is light initiated. We find when BP is exposed to 1-decene and allylpentafluorobenzene (APFB) without illumination, the surface exhibits significant amounts of oxygen and oxidized carbon. This suggests carbon‑oxygen impurities likely have a high affinity for pristine BP surfaces even when reactions are conducted using high-purity reagents under stringent glovebox conditions.
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- Award ID(s):
- 2001611
- PAR ID:
- 10710599
- Publisher / Repository:
- FlatChem (Elsevier Press)
- Date Published:
- Journal Name:
- FlatChem
- Volume:
- 59
- Issue:
- C
- ISSN:
- 2452-2627
- Page Range / eLocation ID:
- 101112
- Subject(s) / Keyword(s):
- black phosphorus molecular functionalization photochemistry photochemical grafting
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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