The Enlightened Path of Nanotechnology:
From 0D to 1D and 2D Nanostructures

Even though nanometer-sized objects have been known for a long time, it is fair to associate the birth of Nanotechnology with the synthesis and identification of the 0D-C₆₀ fullerene molecule in 1985 that was rewarded by the Nobel Prize in 1996 [1]. Yet for many scientists, the real trigger igniting the Nanotechnology Revolution was the reported synthesis and characterization of crystalline 1D multi-wall carbon nanotubes in 1991, 25 years ago [2]. Nanotubes have remained the dominant topic in Physics, Chemistry and Engineering of nanostructures for almost two decades that followed. Intensive search for applications followed and resulted in significant progress. Nanotubes have been shown capable of containing molecules such as C₆₀ [3], uncommon double-helices of selenium [4], and - as chemical reaction vessels - of converting enclosed molecules to diamond nanowires [5]. Unique properties of 1D carbon nanotubes, such as their unprecedented electrical and thermal [6] conductivity, combined with mechanical strength and flexibility, naturally lead to increased interest in their 2D counterpart, graphene. Progress in exfoliation and identification of unprecedented transport properties in graphene [7] resulted in a second Nobel Prize to a carbon nanostructure in 2010. Graphene appeared as an ideal 2D material with one significant shortcoming, namely the absence of a robust and reproducible band gap that is required for electronic applications. After a decade of searching for a remedy, interest has now turned to other 2D semiconductors with an intrinsic band gap that bear promise for 2D electronics applications. Systems capturing scientific interest now range from transition metal dichacogenides such as MoS₂ to very different and unusual group V monolayers including phosphorene [8].