Colloidal semiconductor nanocrystals are versatile nanomaterials, whose properties are determined by their size, shape, composition, and compositional profile [1]. Heterostructured semiconductor nanocrystals (hetero-NCs) are particularly attractive, since they consist of two (or more) different materials joined through heterointerfaces [1]. This allows the spatial localization of photogenerated charge carriers to be manipulated by controlling the band offsets between the materials that are combined at the heterointerface, which opens up remarkable opportunities for tailoring excitons, with important consequences for a number of technologies. The shape of the hetero-NCs is decisive for their properties [1]. Studies carried out over the last few years have demonstrated that charge separation is enhanced in heteronanorods due to their inherent anisotropy, leading to large enhancements in photocatalytic activities and photovoltaic efficiencies [2-3]. To date, the vast majority of the research has focused on Cd-chalcogenide based heteronanorods, which have reached a very mature stage, owing to several decades of intense research [1,4]. However, the widespread use of these materials is severely limited by the intrinsic toxicity of Cd. Alternative heteronanorods based on less-toxic elements are therefore highly needed, but are still underdeveloped.

In our group, we have applied a multistage preparation strategy that allows the combination of different synthesis techniques (e.g., seeded growth and cation exchange) in a sequential manner in order to achieve the targeted preparation of colloidal heteronanorods (HNRs) based on compound copper chalcogenides. This has allowed us to obtain a number of Cu-chalcogenide based HNRs: CuInSe2/CuInS2 dot core/rod shell HNRs [5], CuInS2/ZnS dot core/rod shell HNRs [6], Cu2-xS/ZnS axial heterojunction HNRs, and Cu2-xS/CuInS2 axial heterojunction HNRs. In this talk, we will discuss the specific synthesis strategies and formation mechanisms of each of these nanomaterials, highlighting the general principles that can be used for the rational design of novel Cu-chalcogenide based HNRs. We will also show that composition, size, shape and heteronanostructure control can be used to tailor the opto-electronic properties of these emergent nanomaterials, thereby boosting their potential for photovoltaic and photocatalytic applications.