Photochemical Synthesis
of Particulate Main-Group
Elements and Compounds
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Abstract
Particulate main-group elements (As<sup>0</sup>, Sb<sup>0</sup>, Bi<sup>0</sup>, Pb<sup>0</sup>, Se<sup>0</sup>, Te<sup>0</sup>)
and compounds (Bi<sub>4</sub>Te<sub>3</sub>, Sb<sub><i>x</i></sub>Bi<sub>1–<i>x</i></sub> with 0 ≤ <i>x</i> ≤ 1) are obtained via photoinitiated reduction
under UV irradiation. The synthesis of Bi<sup>0</sup> and Se<sup>0</sup> is exemplarily studied in detail. Here, meso- to micrometer-scaled
particles are obtained with mean diameters of 81(11) nm (Bi<sup>0</sup>) and 1.15(18) μm (Se<sup>0</sup>) in the absence of specific
stabilizers that allow controlling the particle growth. In contrast,
the particle diameter is significantly reduced in the presence of
specific stabilizers (e.g., polyvinylpyrrolidone/PVP for Bi<sup>0</sup>, 2-mercaptoacetid acid/MAA for Se<sup>0</sup>). Now, even the nanoregime
is reached with mean diameters of 4(2) nm (Bi<sup>0</sup>) and 290(39)
nm (Se<sup>0</sup>). The photochemical synthesis is easy to perform
(i.e., aqueous solution/suspension, room temperature, conventional
chlorides/oxides as starting materials) and leads to a homogeneous
particle nucleation, only initiated by UV irradiation as an external
physical trigger. The resulting particulate main group elements and
compounds are characterized by electron microscopy (SEM), dynamic
light scattering (DLS), X-ray powder diffraction (XRD), and energy-dispersive
X-ray (EDX) analysis. The mechanism of the light-initiated reaction
can be clarified by polymerization experiments to involve radicals
as intermediate species
