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 (US) |
|---|---|
| Pages (from-to) | 1050-1055 |
| Number of pages | 6 |
| Journal | Surface Science |
| Volume | 606 |
| Issue number | 13-14 |
| DOIs | |
| State | Published - Jul 2012 |
Funding
This work was supported by the National Science Foundation through the Center for Energetic Non-Equilibrium Chemistry at Interfaces (Grant No. 0943639 ). We thank Dr. Sylvia Ceyer (MIT) for helpful discussions. CPU time was used at supercomputing resources located at: EMSL, a National scientific user facility at Pacific Northwest National Laboratory (PNNL); the Center for Nanoscale Materials at Argonne National Laboratory (ANL); the National Center for Computational Sciences at Oak Ridge National Laboratory (ORNL); and the National Energy Research Scientific Computing Center (NERSC). EMSL is sponsored by the Department of Energy's Office of Biological and Environmental Research located at PNNL. CNM, NCCS, and ORNL are supported by the U.S. Department of Energy, Office of Science , under contracts DE-AC02-06CH11357 , DEAC05-00OR22725 , and DE-AC02-05CH11231 , respectively.
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