Stabilizing Single Ni adatoms on a Two-dimensional Porous Titania Overlayer at the SrTiO$_3$(110) Surface

TL;DR

This study demonstrates the stabilization of single Ni adatoms on a 2D titania-overlayer at SrTiO3(110), revealing their electronic properties and potential for catalytic applications.

Contribution

It introduces a method to stabilize and characterize single Ni adatoms on a reconstructed oxide surface using combined experimental and theoretical approaches.

Findings

Ni adatoms are stabilized at nanopores at room temperature.

Ni adatoms create an in-gap state at 1.9 eV below the conduction band.

Ni adatoms are positively charged and induce upward band bending.

Abstract

Nickel vapor-deposited on the SrTiO$_3$(110) surface was studied using scanning tunneling microscopy, photoemission spectroscopy (PES), and density functional theory calculations. This surface forms a (4 $\times$ 1) reconstruction, composed of a 2-D titania structure with periodic six- and ten-membered nanopores. Anchored at these nanopores, Ni single adatoms are stabilized at room temperature. PES measurements show that the Ni adatoms create an in-gap state located at 1.9 eV below the conduction band minimum and induce an upward band bending. Both experimental and theoretical results suggest that Ni adatoms are positively charged. Our study produces well-dispersed single-adatom arrays on a well-characterized oxide support, providing a model system to investigate single-adatom catalytic and magnetic properties.