Introducing Porosity into Refractory Molybdenum Boride through Controlled Decomposition of a Metastable Mo-Al-B Precursor

Katelyn J. Baumler, Lucas T. Alameda, Rowan R. Katzbaer, Sarah K. O'Boyle, Robert W. Lord, Raymond E. Schaak

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

The high temperatures typically required to synthesize refractory compounds preclude the formation of high-energy morphological features, including nanoscopic pores that are beneficial for applications, such as catalysis, that require higher surface areas. Here, we demonstrate a low-temperature multistep pathway to engineer mesoporosity into a catalytic refractory material. Mesoporous molybdenum boride, α-MoB, forms through the controlled thermal decomposition of nanolaminate-containing sheets of the metastable MAB (metal-aluminum-boron) phase Mo2AlB2and amorphous alumina. Upon heating, the Mo2AlB2layers of the Mo2AlB2-AlOxnanolaminate, which is derived from MoAlB, begin to bridge and decompose, forming inclusions of alumina in a framework of α-MoB. The alumina can be dissolved in aqueous sodium hydroxide in an autoclave, forming α-MoB with empty and accessible pores. Statistical analysis of the morphologies and dimensions of the pores reveals a correlation with grain size, which relates to the pathway by which the alumina inclusions form. The transformation of Mo2AlB2to α-MoB is topotactic due to crystal structure relationships, resulting in a high density of stacking faults that can be modeled to account for the observed experimental diffraction data. Porosity was validated by comparing surface areas and demonstrating catalytic viability for the hydrogen evolution reaction.

Original languageEnglish (US)
Pages (from-to)1423-1432
Number of pages10
JournalJournal of the American Chemical Society
Volume145
Issue number2
DOIs
StatePublished - Jan 18 2023

All Science Journal Classification (ASJC) codes

  • Catalysis
  • General Chemistry
  • Biochemistry
  • Colloid and Surface Chemistry

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