  In the realm of colloidal nanostructures, with its immense capacity for shape
and dimensionality control, the form is undoubtedly a driving factor for the
tunability of optical and electrical properties in semiconducting or metallic
materials. However, influencing the fundamental properties is still challenging
and requires sophisticated surface or dimensionality manipulation. In this
work, we present such a modification for the example of colloidal lead sulphide
nanowires. We show that the electrical properties of lead sulphide
nanostructures can be altered from semiconducting to metallic with indications
of superconductivity, by exploiting the flexibility of the colloidal synthesis
to sculpt the crystal and to form different surface facets. A particular
morphology of lead sulphide nanowires has been synthesized through the
formation of {111} surface facets, which shows metallic and superconducting
properties in contrast to other forms of this semiconducting crystal, which
contain other surface facets ({100} and {110}). This effect, which has been
investigated with several experimental and theoretical approaches, is
attributed to the presence of lead rich {111} facets. The insights promote new
strategies for tuning the properties of crystals as well as new applications
for lead sulphide nanostructures.
