Polarization-dependence of palladium deposition on ferroelectric lithium niobate (0001) surfaces

TL;DR

This study explores how the polarization direction of ferroelectric lithium niobate influences palladium deposition patterns, revealing potential for polarization-controlled catalytic activity.

Contribution

It combines density functional theory and kinetic Monte Carlo simulations to analyze polarization-dependent Pd deposition geometries on LiNbO3 surfaces.

Findings

Pd favors clustering on positive surfaces

Pd disperses on negative surfaces due to diffusion suppression

Deposition geometry affects catalytic activity

Abstract

We investigate the effect of ferroelectric polarization direction on the geometric properties of Pd deposited on the positive and negative surfaces of LiNbO$_3$ (0001). We predict preferred geometries and diffusion properties of small Pd clusters using density functional theory, and use these calculations as the basis for kinetic Monte Carlo simulations of Pd deposition on a larger scale. Our results show that on the positive surface, Pd atoms favor a clustered configuration, while on the negative surface, Pd atoms are adsorbed in a more dispersed pattern due to suppression of diffusion and agglomeration. This suggests that the effect of LiNbO$_3$ polarization direction on the catalytic activity of Pd [J. Phys. Chem. \textbf{88}, 1148 (1984)] is due, at least in part, to differences in adsorption geometry. Further investigations using these methods can aid the search for catalysts whose activities switch reversibly with the polarization of their ferroelectric substrates.