posted on 2023-11-10, 21:31authored byValery Okatenko, Coline Boulanger, Alexander N. Chen, Krishna Kumar, Pascal Schouwink, Anna Loiudice, Raffaella Buonsanti
Nanosized particles of liquid metals are emerging materials
that
hold promise for applications spanning from microelectronics to catalysis.
Yet, knowledge of their chemical reactivity is largely unknown. Here,
we study the reactivity of liquid Ga and Cu nanoparticles under the
application of a cathodic voltage. We discover that the applied voltage
and the spatial proximity of these two particle precursors dictate
the reaction outcome. In particular, we find that a gradual voltage
ramp is crucial to reduce the native oxide skin of gallium and enable
reactive wetting between the Ga and Cu nanoparticles; instead, a voltage
step causes dewetting between the two. We determine that the use of
liquid Ga/Cu nanodimer precursors, which consist of an oxide-covered
Ga domain interfaced with a metallic Cu domain, provides a more uniform
mixing and results in more homogeneous reaction products compared
to a physical mixture of Ga and Cu NPs. Having learned this, we obtain
CuGa2 alloys or solid@liquid CuGa2@Ga core@shell
nanoparticles by tuning the stoichiometry of Ga and Cu in the nanodimer
precursors. These products reveal an interesting complementarity of
thermal and voltage-driven syntheses to expand the compositional range
of bimetallic NPs. Finally, we extend the voltage-driven synthesis
to the combination of Ga with other elements (Ag, Sn, Co, and W).
By rationalizing the impact of the native skin reduction rate, the
wetting properties, and the chemical reactivity between Ga and other
metals on the results of such voltage-driven chemical manipulation,
we define the criteria to predict the outcome of this reaction and
set the ground for future studies targeting various applications for
multielement nanomaterials based on liquid Ga.