The 2D-PnictoChem project has been focused on three primary topics:
i) 2D-Pnictogens nanomaterials (phosphorene, antimonene, and bismuthene);
ii) Hybrid architectures (among others, the combination of 2D-Pnictogens with other nanomaterials: i.e. graphene or layered hydroxides);
iii) Devices and applications. Regarding the first one, new 2D materials based on black phosphorus, antimony, bismuth, layered double hydroxides (LDHs), and graphene have been obtained using different approaches (i.e liquid phase exfoliation, micromechanical exfoliation, and chemical synthesis). A significant achievement has been the bottom-up large-scale colloidal synthesis of antimonene hexagons (Sb-H) (publication #34) and bismuthene hexagons (Bi-H) (publication #54). Indeed, our optimized synthesis yields Sb-H with lateral dimensions up to 6 microns and thicknesses 4–20 nm, comparable to chemical vapor deposition or MBE. High-quality Sb-H with low surface oxidation is demonstrated through mechanical and transport experiments. This achievement offers an alternative route for producing high-quality antimonene with higher yields than previously reported. We have deciphered the oxidation behavior in antimonene, controlling the formation of antimonene oxide/antimonene heterostructures with semiconductor/semimetal character. Bismuthene and Sb-H, obtained through colloidal synthesis, have been found to have highly interesting results in high-quality, hexagonal-shaped particles (Bi-H) with lateral size of ~ 1 µm and thickness between 8 and 20 nm.
The innovative synthesis has been protected by patent in 2021. These results open the door for the development of heavy pnictogens-based technologies since they allow for the first time the large-scale synthesis of high-quality nanosheets for applications in electronics and beyond.
Regarding the second theme, the first bulk reductive covalent functionalization of black phosphorus achieved the highest functionalization degrees and revealed that the P-P bond breaks when P is functionalized.
We have linked Raman spectra changes of bP to its functionalization using solid-state NMR, enabling the quantification of covalent functionalization of black phosphorus using Raman spectroscopy. To produce hybrid heterostructures, we have developed an enormous work of synthesis of other functionalized 2D materials. In fact, we developed the first covalent functionalization of NiFe LDHs, and the first bottom-up synthesis of ultrathin layered hexagonal magnets based on α-CoII hydroxychlorides. We also discovered and patented a scalable synthetic approach for preparing NiFe-LDHs, a crucial oxygen evolution reaction electrocatalyst, which paved the way for Matteco, a spin-off company. We successfully carried out the first multifunctionalization of high-quality graphene with 3 protected different functional groups, preparing hybrid heterostructures assembled through controlled covalent and interface interactions (and not limited to van der Waals forces). Concerning the third topic (devices and applications), the first use of 2D-Pnictogens in organic catalysis, specifically liquid phase exfoliation of phosphorene and antimonene in ionic liquids, has led to excellent catalysts in the alkylation of soft nucleophiles with esters. In electronic devices, the first organic field-effect transistor with functionalized black phosphorus was successfully prepared using a non-covalent pathway and ad-hoc synthesized perylenes.
The study on antimonene oxidation behavior in nanomedicine revealed its effectiveness in influencing cell line cytotoxicity. Top-down (nanosheets and nanoparticles) and bottom-up (Sb-H) synthetic procedures led to diverse oxidation behavior, with hexagonal antimonene being faster oxidized, making it suitable for efficient cancer chemotherapy (publication #66). The study also explores the development and applications of carbon nanomaterials, specifically carbon nano onions (CNOs). It demonstrates CNOs' ability to intercalate alkali metals, paving the way for their potential use in ion batteries (Publication #39). Additionally, the study addresses aggregation and low water solubility issues (Publication #62).
