Abstract
Hydrogen (H) in the subsurface of transition-metal surfaces exhibits unique reactivity for heterogeneously catalyzed hydrogenation reactions. Here, we explore the potential of subsurface H for hydrogenating carbon dioxide (CO 2) on Ni(110). The energetics of surface and subsurface H reacting with surface CO 2 to form formate, carboxyl, and formic acid on Ni(110) is systematically studied using self-consistent, spin-polarized, periodic density functional theory (DFT-GGA-PW91) calculations. We show that on Ni(110), CO 2 can be hydrogenated to formate by surface H. However, further hydrogenation of formate to formic acid by surface H is hindered by a larger activation energy barrier. The relative energetics of hydrogenation barriers is reversed for the carboxyl-mediated route to formic acid. We suggest that the energetics of subsurface H emerging to the surface is suitable for providing the extra energy needed to overcome the barrier to formate hydrogenation. CO 2 hydrogenation to formic acid could take place on Ni(110) when subsurface H is available to react with CO 2. Additional electronic-structure based dynamic calculations would be needed to elucidate the detailed reaction paths for these transformations.
Original language | English |
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Pages (from-to) | 1050-1055 |
Number of pages | 6 |
Journal | Surface Science |
Volume | 606 |
Issue number | 13-14 |
DOIs | |
Publication status | Published - Jul 1 2012 |
Keywords
- Carbon dioxide
- Carboxyl
- Density functional calculations
- Formate
- Hydrogenation
- Nickel
- Subsurface hydrogen
ASJC Scopus subject areas
- Condensed Matter Physics
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Materials Chemistry