  Plasmonic and Mie resonances in subwavelength nanostructures provide an
efficient way to manipulate light below the diffraction limit that has fostered
the growth of plasmonics and nanophotonics. Plasmonic resonances have been
mainly related with the excitation of free charge carriers, initially in
metals, and Mie resonances have been identified in Si nanostructures.
Remarkably, although much less studied, semi-metals, semiconductors and
topological insulators of the p-block enable plasmonic resonances without free
charge carriers and Mie resonances with enhanced properties compared with Si.
In this review, we explain how interband transitions in these materials show a
major role in this duality. We evaluate the plasmonic and Mie performance of
nanostructures made of relevant p-block elements and compounds, especially Bi,
and discuss their promising potential for applications ranging from switchable
plasmonics and nanophotonics to energy conversion, especially photocatalysis.
