Phase-Programmed Nanofabrication: Effect of Organophosphite Precursor Reactivity on the Evolution of Nickel and Nickel Phosphide Nanocrystals
Date
Authors
Major Professor
Advisor
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Authors
Research Projects
Organizational Units
Ames National Laboratory is a government-owned, contractor-operated national laboratory of the U.S. Department of Energy (DOE), operated by and located on the campus of Iowa State University in Ames, Iowa.
For more than 70 years, the Ames National Laboratory has successfully partnered with Iowa State University, and is unique among the 17 DOE laboratories in that it is physically located on the campus of a major research university. Many of the scientists and administrators at the Laboratory also hold faculty positions at the University and the Laboratory has access to both undergraduate and graduate student talent.
The Department of Chemistry seeks to provide students with a foundation in the fundamentals and application of chemical theories and processes of the lab. Thus prepared they me pursue careers as teachers, industry supervisors, or research chemists in a variety of domains (governmental, academic, etc).
History
The Department of Chemistry was founded in 1880.
Dates of Existence
1880-present
Related Units
- College of Liberal Arts and Sciences (parent college)
Journal Issue
Is Version Of
Versions
Series
Department
Abstract
A better understanding of the chemistry of molecular precursors is useful in achieving more predictable and reproducible nanocrystal preparations. Recently, an efficient approach was introduced that consists of fine-tuning the chemical reactivity of the synthetic molecular precursors used, while keeping all other reaction conditions constant. Using nickel phosphides as a research platform, we have studied how the chemical structure and reactivity of a family of commercially available organophosphite precursors (P(OR)3, R = alkyl or aryl) alter the preparation of metallic and metal phosphide nanocrystals. Organophosphites are a versatile addition to the pnictide synthetic toolbox, nicely complementing other available precursors such as elemental phosphorus or trioctylphosphine (TOP). Experimental and computational data show that different organophosphite precursors selectively yield Ni, Ni12P5, and Ni2P and that these phases evolve over time through separate mechanistic pathways. Based on our observations, we propose that nickel phosphide formation requires organophosphite coordination to a nickel precursor, followed by intramolecular rearrangement. We also propose that metallic nickel formation involves outer sphere reduction by uncoordinated organophosphite. These two independent pathways are supported by the fact that preformed Ni nanocrystals do not react with some of the most reactive phosphide-forming organophosphites, failing to evolve into nickel phosphide nanocrystals. Overall, the rate at which organophosphites react with nickel(II) chloride or acetate to form nickel phosphides increases in the order P(OMe)3 < P(OEt)3 < P(OnBu)3 < P(OCH2tBu)3 < P(OiPr)3 < P(OPh)3. Some organophosphites, such as P(OMe)3 or P(OiPr)3, transiently form zerovalent, metallic nickel, while this is the only persistent product observed with the bulky organophosphite P(O-2,4-tBu2C6H4)3. We expect that these results will alleviate the need for time-consuming testing and random optimization of several different reaction conditions, thus enabling a faster development of these and similar pnictide nanomaterials for practical applications.
Comments
Reprinted (adapted) with permission from Chemistry of Materials 27 (2015): A, doi: 10.1021/acs.chemmater.5b03506. Copyright 2015 American Chemical Society.