Multiscale Insights into Amalgamation Synthesis of Intermetallic Nanocrystals via In Situ X-Ray Scattering

Bimetallic nanocrystals are a family of materials with over &gt; 20 000 potential members with a multitude of applications in catalysis, energy conversion and- storage, plasmonics and magnetics.^[1] Recently, a general synthetic approach for colloidal intermetallics via amalgamation was presented,^[2] unlocking up to 1 000 potential new intermetallic nanocrystals. Combining pre-synthesized metal seeds with a liquid metal, the intermetallic compound is formed via fast diffusion dynamics. This overcomes challenges of combining two dissimilar metals at the nanoscale, such as contrasting oxidation potentials or epitaxial constraints. With accurate and predictive control over the size and composition, this synthesis provides access to a wide range of tailor-made intermetallic nanocrystals. Further optimization and expansion of the amalgamation synthesis, however, requires understanding of the process on the atomic as well as on the particle scale.<br/>Here, we turn to in situ small- and wide-angle X-ray scattering as an ideal tool for observing size and size dispersion, as well as crystallinity and phase-dynamics in colloidal systems.^[3–6]. We track multiscale reaction dynamics of colloidal intermetallics (Au-, Ag- and Pd-based alloys) in real time using a tailor-made reactor and reveal unprecedented reaction mechanisms in the formation of intermetallics. Furthermore, we also provide a toolbox for in situ studies of nearly every nanocrystal synthesis since the combination of reactor and in situ scattering can be applied to highly air- and moisture-sensitive protocols at temperatures up to 330 °C and down to millisecond timescales.<br/><br/>[1] K. D. Gilroy, A. Ruditskiy, H. C. Peng, D. Qin, Y. Xia, <i>Chem. </i><i>Rev.</i> <b>2016</b>, <i>116</i>, 10414.<br/>[2] J. Clarysse, A. Moser, O. Yarema, V. Wood, M. Yarema, <i>Sci. Adv.</i> <b>2021</b>, <i>7</i>.<br/>[3] X. Chen, J. Wang, R. Pan, S. Roth, S. Förster, <i>J. Phys. Chem. C</i> <b>2021</b>, <i>125</i>, 1087.<br/>[4] M. P. Campos, J. De Roo, M. W. Greenberg, B. M. McMurtry, M. P. Hendricks, E. Bennett, N. Saenz, M. Y. Sfeir, B. Abécassis, S. K. Ghose, J. S. Owen, <i>Chem. Sci.</i> <b>2022</b>, <i>13</i>, 4555.<br/>[5] Q. A. Akkerman, T. P. T. Nguyen, S. C. Boehme, F. Montanarella, D. N. Dirin, P. Wechsler, F. Beiglböck, G. Rainò, R. Erni, C. Katan, J. Even, M. V. Kovalenko, <i>Science</i> <b>2022</b>, <i>377</i>, 1406.<br/>[6] M. Strach, V. Mantella, J. R. Pankhurst, P. Iyengar, A. Loiudice, S. Das, C. Corminboeuf, W. Van Beek, R. Buonsanti, <i>J. Am. </i><i>Chem. Soc.</i> <b>2019</b>, <i>141</i>, 16312.