Multi-Step Topochemical Pathway to Metastable Mo2AlB2 and Related Two-Dimensional Nanosheet Heterostructures

Lucas T. Alameda, Robert W. Lord, Jordan A. Barr, Parivash Moradifar, Zachary P. Metzger, Benjamin C. Steimle, Cameron F. Holder, Nasim Alem, Susan B. Sinnott, Raymond Edward Schaak

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

The rational synthesis of metastable inorganic solids, which is a grand challenge in solid-state chemistry, requires the development of kinetically controlled reaction pathways. Topotactic strategies can achieve this goal by chemically modifying reactive components of a parent structure under mild conditions to produce a closely related analogue that has otherwise inaccessible structures and/or compositions. Refractory materials, such as transition metal borides, are difficult to structurally manipulate at low temperatures because they generally are chemically inert and held together by strong covalent bonds. Here, we report a multistep low-temperature topotactic pathway to bulk-scale Mo2AlB2, which is a metastable phase that has been predicted to be the precursor needed to access a synthetically elusive family of 2-D metal boride (MBene) nanosheets. Room-temperature chemical deintercalation of Al from the stable compound MoAlB (synthesized as a bulk powder at 1400 °C) formed highly strained and destabilized MoAl1-xB, which was size-selectively precipitated to isolate the most reactive submicron grains and then annealed at 600 °C to deintercalate additional Al and crystallize Mo2AlB2. Further heating resulted in topotactic decomposition into bulk-scale Mo2AlB2-AlOx nanolaminates that contain Mo2AlB2 nanosheets with thickness of 1-3 nm interleaved by 1-3 nm of amorphous aluminum oxide. The combination of chemical destabilization, size-selective precipitation, and low-temperature annealing provides a potentially generalizable kinetic pathway to metastable variants of refractory compounds, including bulk Mo2AlB2 and Mo2AlB2-AlOx nanosheet heterostructures, and opens the door to other previously elusive 2-D materials such as 2-D MoB (MBene).

Original languageEnglish (US)
Pages (from-to)10852-10861
Number of pages10
JournalJournal of the American Chemical Society
Volume141
Issue number27
DOIs
StatePublished - Jul 10 2019

Fingerprint

Nanosheets
Heterojunctions
Boron Compounds
Temperature
Borides
Refractory materials
Metals
Synthetic Chemistry Techniques
Covalent bonds
Metastable phases
Aluminum Oxide
Powders
Heating
Transition metals
Annealing
Decomposition
Aluminum
Kinetics
Oxides
Chemical analysis

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Alameda, Lucas T. ; Lord, Robert W. ; Barr, Jordan A. ; Moradifar, Parivash ; Metzger, Zachary P. ; Steimle, Benjamin C. ; Holder, Cameron F. ; Alem, Nasim ; Sinnott, Susan B. ; Schaak, Raymond Edward. / Multi-Step Topochemical Pathway to Metastable Mo2AlB2 and Related Two-Dimensional Nanosheet Heterostructures. In: Journal of the American Chemical Society. 2019 ; Vol. 141, No. 27. pp. 10852-10861.
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abstract = "The rational synthesis of metastable inorganic solids, which is a grand challenge in solid-state chemistry, requires the development of kinetically controlled reaction pathways. Topotactic strategies can achieve this goal by chemically modifying reactive components of a parent structure under mild conditions to produce a closely related analogue that has otherwise inaccessible structures and/or compositions. Refractory materials, such as transition metal borides, are difficult to structurally manipulate at low temperatures because they generally are chemically inert and held together by strong covalent bonds. Here, we report a multistep low-temperature topotactic pathway to bulk-scale Mo2AlB2, which is a metastable phase that has been predicted to be the precursor needed to access a synthetically elusive family of 2-D metal boride (MBene) nanosheets. Room-temperature chemical deintercalation of Al from the stable compound MoAlB (synthesized as a bulk powder at 1400 °C) formed highly strained and destabilized MoAl1-xB, which was size-selectively precipitated to isolate the most reactive submicron grains and then annealed at 600 °C to deintercalate additional Al and crystallize Mo2AlB2. Further heating resulted in topotactic decomposition into bulk-scale Mo2AlB2-AlOx nanolaminates that contain Mo2AlB2 nanosheets with thickness of 1-3 nm interleaved by 1-3 nm of amorphous aluminum oxide. The combination of chemical destabilization, size-selective precipitation, and low-temperature annealing provides a potentially generalizable kinetic pathway to metastable variants of refractory compounds, including bulk Mo2AlB2 and Mo2AlB2-AlOx nanosheet heterostructures, and opens the door to other previously elusive 2-D materials such as 2-D MoB (MBene).",
author = "Alameda, {Lucas T.} and Lord, {Robert W.} and Barr, {Jordan A.} and Parivash Moradifar and Metzger, {Zachary P.} and Steimle, {Benjamin C.} and Holder, {Cameron F.} and Nasim Alem and Sinnott, {Susan B.} and Schaak, {Raymond Edward}",
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Alameda, LT, Lord, RW, Barr, JA, Moradifar, P, Metzger, ZP, Steimle, BC, Holder, CF, Alem, N, Sinnott, SB & Schaak, RE 2019, 'Multi-Step Topochemical Pathway to Metastable Mo2AlB2 and Related Two-Dimensional Nanosheet Heterostructures', Journal of the American Chemical Society, vol. 141, no. 27, pp. 10852-10861. https://doi.org/10.1021/jacs.9b04726

Multi-Step Topochemical Pathway to Metastable Mo2AlB2 and Related Two-Dimensional Nanosheet Heterostructures. / Alameda, Lucas T.; Lord, Robert W.; Barr, Jordan A.; Moradifar, Parivash; Metzger, Zachary P.; Steimle, Benjamin C.; Holder, Cameron F.; Alem, Nasim; Sinnott, Susan B.; Schaak, Raymond Edward.

In: Journal of the American Chemical Society, Vol. 141, No. 27, 10.07.2019, p. 10852-10861.

Research output: Contribution to journalArticle

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T1 - Multi-Step Topochemical Pathway to Metastable Mo2AlB2 and Related Two-Dimensional Nanosheet Heterostructures

AU - Alameda, Lucas T.

AU - Lord, Robert W.

AU - Barr, Jordan A.

AU - Moradifar, Parivash

AU - Metzger, Zachary P.

AU - Steimle, Benjamin C.

AU - Holder, Cameron F.

AU - Alem, Nasim

AU - Sinnott, Susan B.

AU - Schaak, Raymond Edward

PY - 2019/7/10

Y1 - 2019/7/10

N2 - The rational synthesis of metastable inorganic solids, which is a grand challenge in solid-state chemistry, requires the development of kinetically controlled reaction pathways. Topotactic strategies can achieve this goal by chemically modifying reactive components of a parent structure under mild conditions to produce a closely related analogue that has otherwise inaccessible structures and/or compositions. Refractory materials, such as transition metal borides, are difficult to structurally manipulate at low temperatures because they generally are chemically inert and held together by strong covalent bonds. Here, we report a multistep low-temperature topotactic pathway to bulk-scale Mo2AlB2, which is a metastable phase that has been predicted to be the precursor needed to access a synthetically elusive family of 2-D metal boride (MBene) nanosheets. Room-temperature chemical deintercalation of Al from the stable compound MoAlB (synthesized as a bulk powder at 1400 °C) formed highly strained and destabilized MoAl1-xB, which was size-selectively precipitated to isolate the most reactive submicron grains and then annealed at 600 °C to deintercalate additional Al and crystallize Mo2AlB2. Further heating resulted in topotactic decomposition into bulk-scale Mo2AlB2-AlOx nanolaminates that contain Mo2AlB2 nanosheets with thickness of 1-3 nm interleaved by 1-3 nm of amorphous aluminum oxide. The combination of chemical destabilization, size-selective precipitation, and low-temperature annealing provides a potentially generalizable kinetic pathway to metastable variants of refractory compounds, including bulk Mo2AlB2 and Mo2AlB2-AlOx nanosheet heterostructures, and opens the door to other previously elusive 2-D materials such as 2-D MoB (MBene).

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