Colloidal chemical bottom-up synthesis routes of pnictogen (As, Sb, Bi) nanostructures with tailored properties and applications: a summary of the state of the art and main insights
Pnictogens are the chemical elements of group 15 of the periodic table. Such materials have been receiving interest thanks to their semiconducting electronic properties, especially exhibited when possessing a 2D monolayer configuration. In particular, arsenic (As) and antimony (Sb) exhibit a metalloid behavior, whereas bismuth (Bi) is considered as a metal. Typically top-down methods, with sonication and liquid-phase exfoliation being prevalent, have been employed to prepare two-dimensional pnictogen nanostructures. Still, bottom-up approaches such as colloidal chemistry are also able to produce nanosheets as well as smaller nanoscale particles of these elements. Such nanoparticles possess remarkable thermoelectric and photocatalytic properties, enabling their use in fields such as photothermal therapy, catalysis, electrocatalysis and sensing. In addition, ‘wet-chemical’ routes, especially those involving organic solvents, often lead to particles with well-defined features such as narrow monodispersity. Therefore in this Highlight we present the chemical bottom-up routes to produce pnictogen (As, Sb, Bi) nanostructures of either spherical or anisotropic shape as well as 2D nanosheets. The relation of the employed synthetic routes with the corresponding properties and the suitability for a range of applications are also discussed in a critical manner. Finally, the synthesis of pnictogen-based intermetallics with a focus on promising materials for electrocatalytic use such as PtBi2 and PdBi2 is also highlighted.