# Phases and Architectures in Metal/Metal Oxide Systems Driven by Strong Metal–Support Interactions

## TL;DR

This paper explores how metal/metal oxide catalysts change under reducing conditions using computational methods to understand and design better catalytic materials.

## Contribution

A systematic computational approach combining DFT and machine learning to study SMSI and propose descriptors for phase diversity.

## Key findings

- Phase diversity in SMSI structures arises from competition between oxide and alloy formation.
- Suboxide layer properties determine the final architecture and electronic properties of the material.
- Two descriptors are proposed to explain and predict phase behavior in metal/metal oxide interfaces.

## Abstract

Metal oxide supported metal catalysts are widely applied
in industrial
processes. Many of these materials dynamically evolve under reducing
atmospheres, leading to metal nanoparticles partially or fully encapsulated
by metal oxide shells, impacting catalytic performance. This phenomenon
is known as strong metal–support interaction (SMSI) and is
thermodynamically driven. However, understanding the metal/metal oxide
interfaces derived from the broad and flexible compositional space
and the large structural changes in SMSI structures is difficult to
monitor experimentally. Here, we use density functional theory together
with machine learning interatomic potentials and global minima optimization
to investigate SMSI by building a set of interfaces between common
catalytic metals (Ni, Pd, Pt) and reducible metal oxides (r-TiO2, CeO2, In2O3) at different
reduction levels. Phase diversity arises from the competition between
the formation of different metal oxides or binary alloys, while the
local properties of the suboxide layers are responsible for the final
architecture and composition determining the electronic properties
of the material. Two descriptors related to the competition between
alloy and oxide formation are proposed to elucidate the phase diversity.
Our work provides a systematic approach to advance the design of SMSI-based
catalytic materials by offering insights into the atomic-level architecture
of the metal/metal oxide interfaces.