0000000000189901
AUTHOR
Katarzyna A. Kacprzak
First-principles simulations of hydrogen peroxide formation catalyzed by small neutral gold clusters.
Energetics and dynamical pathways for hydrogen peroxide formation from H(2) and O(2) bound to neutral gold dimers and tetramers have been investigated by applying several strategies: T = 0 K geometry optimizations, constrained Car-Parrinello molecular dynamics simulations at T = 300 K and metadynamics at T = 300 K. The competing reaction channels for water and hydrogen peroxide formation have been found and characterized. In each case, the reaction barriers for Au cluster catalyzed proton transfer are less than 1 eV. Water formation is a competitive reaction channel, and the relative weight of H(2)O and H(2)O(2) products may depend on the chosen Au cluster size. Dynamic simulations demonstr…
Quantum size effects in ambient CO oxidation catalysed by ligand-protected gold clusters
Finely dispersed nanometre-scale gold particles are known to catalyse several oxidation reactions in aerobic, ambient conditions. The catalytic activity has been explained by various complementary mechanisms, including support effects, particle-size-dependent metal-insulator transition, charging effects, frontier orbital interactions and geometric fluxionality. We show, by considering a series of robust and structurally well-characterized ligand-protected gold clusters with diameters between 1.2 and 2.4 nm, that electronic quantum size effects, particularly the magnitude of the so-called HOMO-LUMO energy gap, has a decisive role in binding oxygen to the nano-catalyst in an activated form. T…
A density functional investigation of thiolate-protected bimetal PdAu24(SR)18z clusters: doping the superatom complex
Structure, electronic properties, optical absorption and charging properties of methylthiolate-protected bimetal PdAu(24)(SR)(18)(z) (R = Me) clusters with various charge states (-3or=zor= +3) are investigated by using density functional theory. The results are compared to properties of the well-understood singly anionic pure gold complex Au(25)(SR)(18)((-1)) [J. Akola, M. Walter, H. Häkkinen and H. Grönbeck, J. Am. Chem. Soc., 2008, 130, 3756]. The atomic structure of this all-gold complex can be written in a "divide-and-protect" way [H. Häkkinen, M. Walter and H. Grönbeck, J. Phys. Chem. B, 2006, 110, 9927] as Au(13)[Au(2)(SR)(3)](6)((-1)) where 6 v-shaped Au(2)(SR)(3) ligands protect the…