Spectroscopy of van der Waals nanomaterials: Opportunities and challenges

The study of van der Waals (vdW) materials has seen increased interest in recent years due to the wide range of uses for these materials because of their unique mechanical, electronic, and optical properties. This area has recently expanded further into studying the behavior of vdW nanomaterials as decreasing dimensions open up opportunities to interact with these materials in new ways. However, measuring the band structures of nanomaterials, which is key to understanding how confinement affects material properties and interactions, comes with several challenges. In this review, we survey a range of techniques for synthesizing and characterizing vdW nanomaterials, in order to outline the key material and characterization challenges. This includes controlling the Fermi level in vdW nanoparticles, preparing these particles for either ensemble or individual particle measurement, as well as protecting the pristine surface from oxidation.