Nanoparticles are indispensable to modern research and technology, spanning nearly all fields of investigation and application. But nanoparticle research and development suffers from the systemic problem of lacking a general synthetic means that accommodates the breadth of the periodic table. We present the formation and use of a new family of reagents that provides the foundation for a universal approach to nanomaterial synthesis; with nanoparticle products ranging from simple elements (i.e. Fe and Co) to traditionally challenging elements (i.e. Ir, Mg and Sn) to the formation of alloy nanoparticles (i.e. MnBi). By using lithium borohydride (LiBH4) in a gentle mechanochemical process, we obtain an anionic elemental reagent complex (AERC) with the general formula R(LiBH4)x (where x = 1 to 4). AERCs are a highly versatile and useful reagent species which can incorporate metal, metalloid and non-metal elements (represented as R in the empirical formula) from columns II through XVI of the periodic table. XPS characterization of AERCs revealed a reduction in the R-species binding energy ranging from 0.3 eV for Fe 2p transition to 5.4 eV for the Ge 3d transition. An example of tungsten-AERC XPS data, versus tungsten metal, is shown in Figure 1a illustrating the anionic shift in the metal. This indicates a clear interaction with LiBH4 that results in electron density being transferred to the R-species. FT-IR analysis indicates the tetrahedral BH4- anion is still present, and stable, in the AERCs. This transfer of electron density leads to a state that allows the AERCs to form easily, and be used in either a reactive or dissociative means for the production of either non-alloyed or alloyed nanoparticles of the R-specie. A sample TEM image of Mg nanoparticles, made from Mg-AERC, is shown in Figure 1b. The diversity the AERC functionality and nanoparticles synthesized is demonstrated by examples of their use in the fields of rare-earth-free magnetics, energy storage, and catalytic materials.

Anionic element reagent complexes: A generic reagent platform for nanoparticle synthesis

249th National Meeting (2015)

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