Two-Dimensional Transition Metal Silicate Formed on Ru (0001) by Hydrogenation

TL;DR

This study uses density functional theory to explore hydrogenation as a method to weaken substrate-overlayer interactions, aiming to facilitate the exfoliation of two-dimensional transition-metal silicates on Ru(0001).

Contribution

It systematically investigates hydrogenation levels' effects on structure and thermodynamics, providing insights into conditions for feasible exfoliation of 2D transition-metal silicates.

Findings

Hydrogenation reduces substrate-overlayer interactions.

Fe remains primarily in the 3+ oxidation state after hydrogenation.

Infrared spectroscopy shifts correlate with hydrogenation levels.

Abstract

Bottom-up synthesis of two-dimensional transition-metal silicates has been challenging due to strong overlayer-substrate interactions, which prevents the exfoliation of the overlayer. Here, using density functional theory calculations, we systematically investigate the hydrogenation of the overlayer as a way to decrease the substrate and overlayer interactions. Using the Fe$_2$Si$_2$O$_8\cdot$O/Ru(0001) structure as our starting point Wlodarczyk et. al. [1], we study hydrogenation levels up to Fe$_2$Si$_2$O$_9$H$_4\cdot$/Ru(0001). Structural and thermodynamical properties are studied at different hydrogenation levels to show under which conditions, the exfoliation can be feasible. Simulated core-level shifts show that Fe is primarily in 3+ state through the hydrogenation of Fe$_2$Si$_2$O$_8\cdot$O/Ru(0001). Simulated reflection adsorption infrared spectroscopy (RAIRS) yield distinctive shifts in vibrational properties with increasing hydrogenation which can guide experiments. [1] R. Wlodarczyk et al., "Atomic structure of an ultrathin Fe-silicate film grown on a metal: A monolayer of clay?", J. Am. Chem. Soc., 135, 19222, (2013).