TY  - JOUR
A1  - Wirth, Jonas
A1  - Saalfrank, Peter
T1  - The chemistry of water on alpha-alumina kinetics and nuclear quantum effects from first principles
JF  - The journal of physical chemistry : C, Nanomaterials and interfaces
N2  - Water adsorption on an alumina (alpha-Al2O3) surface is studied here from first principles using periodic density functional theory in the generalized gradient approximation. Two different coverage regimes, low and high, are considered. For the low-coverage regime (with a coverage of 1/4 with respect to the number of coordinatively unsaturated Al sites), possible reactions at the surface such as dissociation, rotation, and diffusion of water and its fragments are investigated, using first principles thermodynamics and kinetics. A microkinetic model is set up with rates calculated from Eyring's transition state theory in order to cover a wide range of time scales. Special emphasis of this study is on the magnitude of quantum effects and on anharmonic corrections, particularly for reactions and dynamics. These have often been neglected in the past for water/alumina systems but can influence the system. This is particularly true for processes involving hydrogen atoms, where, for example, tunneling corrections to reaction rates are found to be important even at room temperature. For a higher-coverage regime (with a coverage of 2 ML), hydrogen dynamics becomes even more complex and is characterized, e.g., by concerted atom motion, strong anharmonicity, and delocalization. In this regime, classical molecular dynamics becomes questionable as well as quantum mechanical treatments based on the harmonic approximation.
Y1  - 2012
U6  - https://doi.org/10.1021/jp310234h
SN  - 1932-7447
VL  - 116
IS  - 51
SP  - 26829
EP  - 26840
PB  - American Chemical Society
CY  - Washington
ER  -