Stabilizing Single Ni Adatoms on a Two-Dimensional Porous Titania Overlayer at the SrTiO₃(110) Surface

Abstract

Nickel vapor-deposited on the SrTiO3(110) surface was studied using scanning tunneling microscopy, photoemission spectroscopy (PES), and density functional theory calculations. This surface forms a (4 × 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.

Recent Progress in Single‐Atom Catalysts for Photocatalytic Water Splitting

“…The interaction between single metal atoms and supports can change the local electronic structures of SACs, further influencing catalytic performances. [75,76] The single metal atoms of SACs can interact with the coordination atoms from supports via the overlap of electronic orbitals, leading to the electron transfer and charge redistribution between single metal atoms and supports and further lowering reaction barriers. [77][78][79][80] To prepare more high-performance SACs for photocatalytic hydrogen evolution, a comprehensive understanding of the photochemical process on SACs is necessary.…”

Nickel-Oxide-Modified SrTiO3(110)-(4 × 1) Surfaces and Their Interaction with Water

“…Evaporation of Ni (red curve) shifts all spectral features to lower binding energies (by 0.22 ± 0.15 eV) and an in-gap state is formed. The adsorption of single Ni adatoms at the SrTiO 3 (110)-(4 × 1) surface has been studied recently, 15 showing that isolated Ni adatoms are formed up to a coverage of 0.05 Å [see Figure 2 b].…”

“…Ni adatoms can adsorb either at the center of (4 × 1) rows (six-membered TiO 4 rings) or on their sides, in proximity of the dark trenches (ten-membered TiO 4 rings). 15 …”

Single Metal Atom Photocatalysis

“…Anchoring single metal atoms at confined space, such as nanopores or micropores, is an effective strategy to restrict the migration and agglomeration of isolated metal atoms. For example, by utilizing the 2D titania structure with periodic 6‐ or 10‐membered nanopores on the reconstructed SrTiO 3 (110) surface, Wang et al anchored Ni single atoms in the open nanopores at room temperature . Another interesting support is mesoporous polymeric graphitic carbon nitride (mpg‐C 3 N 4 ).…”

“…When single Ni atoms were anchored on the Nb‐doped SrTiO 3 (110) surface, an in‐gap surface states, which mainly originated from the Ni 3d orbital, at a binding energy of 1.9 eV was introduced. As these in‐gap states were below the Fermi level, the electrons from Nb atoms in SrTiO 3 were transferred to the surface states, resulting in the upward band bending …”