Kinetics of palladium particles on LiNbO3: an origin of the polarization-dependent catalysis

Using ab-initio calculations and kinetic Monte Carlo simulations, we demonstrate that the deposition geometries of palladium are strongly dependent on the polarization direction of the LiNbO3 substrate. Different stoichiometries and atomic structures of the positively and the negatively polarized substrates cause substantially different bonding configurations of palladium and energy barriers for the movement of Pd clusters. Our simulations predict that palladium atoms form bulky clusters on the positive surface, while they are deposited in a dispersed or planar manner on the negative surface at moderate temperature. We suggest that Inoue and coworkers’ observation [J. Phys. Chem. 88, 1148 (1984)] that the catalytic activity of palladium depends on polarization direction of LiNbO3 substrate is, at least in part, due to differences in the geometric structures of palladium and the LiNbO3 surface.