Contributed
High yield, bottom-up synthesis of layered metal sulfides, phosphides, and selenides using thermal annealing and applications in electronics and electrochemistry

Since the graphene Nobel Prize in 2010, the focus has not shifted to the synthesis of other non-carbon few/mono-layers exhibiting a variety of bandgaps and semiconducting properties (e.g., n or p type).

Here we show a combined bottom-up and top-down approach where (a) we synthesize in one step high yields of bulk layered materials by annealing a metal in the presence of a gas precursor (sulfur, phosphorous, or selenium) and (b) we exfoliate and dropcast few/mono-layers on a substrate from a sonicated mixture of our material in a specific solvent. It is interesting to note that, besides the structure being 2D layered, the properties of the nanomaterials synthesized slightly differ from the materials with the same stoichiometry synthesized using conventional chemical methods.

For instance, we synthesized Cu₉S₅ and showed that is a highly doped, p-type material. This is critical to fabricate devices such as p-n junctions and heterojunctions, since most of the recently discovered and studied layered materials such as MoS₂, or MoSe₂ are n-type, while few materials, such as phosphorene, which suffers from rapid oxidation, are p-type. We tested the synthesized Cu₉S₅ as an electrode for Li-ion battery and published the results in Chemistry of Materials (Vol. 30, 2379−2388, 2018)

We also synthesized high yields of bulk layered silver sulfide (Ag₂S) for hydrogen evolution reaction (HER) and copper phosphide (Cu₃P) as supercapacitor and selenides (initial results).

In this talk, we will discuss the synthesis, the extensive characterizations, the applications tested, and the promise of this technique for the fabrication of bulk materials for energy application and of heterojunctions based on monolayers for future electronic devices.