hide
Free keywords:
Catalyst activity; Charge transfer; Chemical bonds; Density functional theory; Gold nanoparticles; Molecular dynamics; Nanocatalysts; Reaction kinetics; TiO2 nanoparticles; Titanium dioxide, Ab initio molecular dynamics simulation; Defects in semiconductors; Electron transfer; Electronic charges; Electronic polarization effect; Hybrid functionals; Oxidation reactions; Positive charges, Oxygen vacancies
Abstract:
Gold nanoparticles supported on reduced TiO 2 (110) surfaces are widely used as catalysts for oxidation reactions. Despite extensive studies, the role of oxygen vacancies in such systems remains elusive and is controversially discussed. Combining ab initio molecular dynamics simulations with methods originally developed to describe defects in semiconductor physics we study how the electronic charge originally located at the vacancy modifies the charge on the cluster. Despite differences resulting from the employed level of density functional theory (namely semilocal/GGA, GGA + U, and hybrid functionals), we consistently find that the Au clusters remain either neutral or acquire a positive charge. The intuitively expected electron transfer from the oxygen vacancy to the gold cluster can be safely ruled out. Analyzing these findings, we discuss the role of the oxygen vacancy in the bonding between Au clusters and support and the catalytic activity of the system. © 2019 American Chemical Society.
