Precious Metal Dioxide Nanosheets: Bridging the Gap between Solution Chemistry and Solid-State Two-Dimensional Materials

TL;DR

This paper reveals the atomic structure of precious metal dioxide nanosheets and how their properties are linked to their unique structural features.

Contribution

The study establishes a structure–property relationship for PMD nanosheets using PDF analysis and identifies subtle short-range order as a key design factor.

Findings

Platinate and iridate nanosheets adopt a T-MoS2-type crystal structure.

Structural polymorphism is governed by elemental characteristics, not redox states.

Subtle short-range order in metal atom positions influences material properties.

Abstract

Unraveling the atomic structures of chemically exfoliated
precious
metal dioxide (PMD) nanosheets is the key to understanding their diverse
properties and realizing their potential in applications like catalysis.
Using pair distribution function (PDF) analysis, we have solved the
structures of platinate and iridate nanosheets, revealing they both
adopt a T-MoS2-type crystal structure. This discovery not
only establishes a crucial structural analogy to well-understood transition
metal dichalcogenides (TMDs) but, more importantly, allows us to explain
the origins of their distinct properties. Our calculations based on
these structures correctly predict that the platinate nanosheet is
a yellow semiconductor, while the iridate nanosheet is a blue semimetal.
Having established this powerful structure–property relationship,
we further probed the unique chemical nature of these materials. We
found that the structural polymorphism (T- vs T′-type) is governed
by intrinsic elemental characteristics, rather than simple redox states
as explored by in situ experiments. Instead of large-scale distortions,
these nanosheets exhibit subtle short-range order (SRO) in their metal
atom positions. This work provides a robust methodology for PMD research
and highlights that chemically imparted features like SRO are key
to designing the next generation of 2D materials.

Figures