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Reactive Oxygen Species Sequestration Induced Synthesis of β-PbO and Its Polymorphic Transformation to α-PbO at Atomically Thin Regimes

journal contribution
posted on 2023-02-20, 03:19 authored by A Ingle, M Singh, Sherif AbbasSherif Abbas, BJ Murdoch, EL Harrop Mayes, MJ Sapountzis Spencer, R Ramanathan, V Bansal
The emergence of attractive properties in materials at atomically thin regimes has seen an ongoing interest in two-dimensional (2D) materials. An aspect that has lacked focused attention is the effect of 2D material thickness on its crystal structure. As several layered materials naturally exist in mixed metastable phases, it raises an important question of whether a specific polymorph of these mixed-phase materials will be favored at atomically thin limits. This work attempts to address this issue by employing lead monoxide as a model 2D polymorphic system. We propose a reactive oxygen species (ROS) sequestration-mediated liquid-phase exfoliation (LPE) strategy for the facile synthesis of ultrathin PbO. This is followed by a suite of microscopic and spectroscopic analyses of the PbO nanosheets that reveals the polymorphic transformation of orthorhombic (β) PbO to its tetragonal (α) analogue with reduction in nanosheet thickness. The transformation process reveals an interesting crystal structure of ultrathin 2D PbO where [001]-oriented domains of α-PbO coexist alongside [100]-oriented regions of β-PbO. Density functional theory (DFT) calculations support our experimental data by revealing a higher thermodynamic stability of the tetragonal phase in PbO monolayers. These findings are likely to instigate interest in carefully evaluating the crystal structures of ultrathin 2D materials while promoting research in understanding the phase transformation across a range of 2D crystals.

History

Journal

ACS Nano

Volume

16

Pagination

10679-10691

Location

United States

ISSN

1936-0851

eISSN

1936-086X

Language

English

Publication classification

C1 Refereed article in a scholarly journal

Issue

7

Publisher

AMER CHEMICAL SOC