2 research outputs found
Coexisting Surface Phases and Coherent One-Dimensional Interfaces on BaTiO<sub>3</sub>(001)
Coexistence of surface reconstructions is important due to the diversity in kinetic and thermodynamic processes involved. We identify the coexistence of kinetically accessible phases that are chemically identical and form coherent interfaces. Here, we establish the coexistence of two phases, <i>c</i>(2 × 2) and <i>c</i>(4 × 4), in BaTiO<sub>3</sub>(001) with atomically resolved Scanning Tunneling Microscopy (STM). First-principles thermodynamic calculations determine that TiO adunits and clusters compose the surfaces. We show that TiO diffusion results in a kinetically accessible <i>c</i>(2 × 2) phase, while TiO clustering results in a kinetically and thermodynamically stable <i>c</i>(4 × 4) phase. We explain the formation of domains based on the diffusion of TiO units. The diffusion direction determines the observed 1D coherent interfaces between <i>c</i>(2 × 2) and <i>c</i>(4 × 4) reconstructions. We propose atomic models for the <i>c</i>(2 × 2), <i>c</i>(4 × 4), and 1D interfaces
Synergistic Oxygen Evolving Activity of a TiO<sub>2</sub>‑Rich Reconstructed SrTiO<sub>3</sub>(001) Surface
In
addition to composition, the structure of a catalyst is another
fundamental determinant of its catalytic reactivity. Recently, anomalous
Ti oxide-rich surface phases of ternary oxides have been stabilized
as nonstoichiometric epitaxial overlayers. These structures give rise
to different modes of oxygen binding, which may lead to different
oxidative chemistry. Through density functional theory investigations
and electrochemical measurements, we predict and subsequently show
that such a TiO<sub>2</sub> double-layer surface reconstruction enhances
the oxygen evolving activity of the perovskite-type oxide SrTiO<sub>3</sub>. Our theoretical work suggests that the improved activity
of the restructured TiO<sub>2</sub>(001) surface toward oxygen formation
stems from (i) having two Ti sites with distinct oxidation activity
and (ii) being able to form a strong O–O moiety (which reduces
overbonding at Ti sites), which is a direct consequence of (iii) having
a labile lattice O that is able to directly participate in the reaction.
Here, we demonstrate the improvement of the catalytic performance
of a well-known and well-studied oxide catalyst through more modern
methods of materials processing, predicted through first-principles
theoretical modeling