Periodic Reporting for period 3 - 2D-PnictoChem (Chemistry and Interface Control of Novel 2D-Pnictogen Nanomaterials)
Reporting period: 2021-11-01 to 2023-04-30
2D-PnictoChem aims at exploring the Chemistry of a novel class of graphene-like 2D layered elemental materials of group 15, the pnictogens: P, As, Sb, and Bi. In the last few years, these materials have taken the field of Materials Science by storm since they can outperform and/or complement graphene properties. Their strongly layer-dependent unique properties range from semiconducting to metallic, including high carrier mobilities, tunable bandgaps, strong spin-orbit coupling or transparency. However, the Chemistry of pnictogens is still in its infancy, remaining largely unexplored. This is the niche that 2D-PnictoChem aims to fill.
By mastering the interface chemistry, we will develop the assembly of 2D-pnictogens in complex hybrid heterostructures for the first time. Success will rely on a cross-disciplinary approach combining both Inorganic- and Organic Chemistry with Solid-state Physics, including: 1) Synthetizing and exfoliating high quality ultra-thin layer pnictogens, providing reliable access down to the monolayer limit. 2) Achieving their chemical functionalization via both non-covalent and covalent approaches in order to tailor at will their properties, decipher reactivity patterns and enable controlled doping avenues. 3) Developing hybrid architectures through a precise chemical control of the interface, in order to promote unprecedented access to novel heterostructures. 4) Exploring novel applications concepts achieving outstanding performances. Along this front, 2D-PnictoChem addresses challenges in batteries, electronic devices and catalysis. These are all priorities in the European Union agenda aimed at securing an affordable, clean energy future by developing more efficient hybrid systems for batteries, electronic devices or applications in catalysis.
By mastering the interface chemistry, we will develop the assembly of 2D-pnictogens in complex hybrid heterostructures for the first time. Success will rely on a cross-disciplinary approach combining both Inorganic- and Organic Chemistry with Solid-state Physics, including: 1) Synthetizing and exfoliating high quality ultra-thin layer pnictogens, providing reliable access down to the monolayer limit. 2) Achieving their chemical functionalization via both non-covalent and covalent approaches in order to tailor at will their properties, decipher reactivity patterns and enable controlled doping avenues. 3) Developing hybrid architectures through a precise chemical control of the interface, in order to promote unprecedented access to novel heterostructures. 4) Exploring novel applications concepts achieving outstanding performances. Along this front, 2D-PnictoChem addresses challenges in batteries, electronic devices and catalysis. These are all priorities in the European Union agenda aimed at securing an affordable, clean energy future by developing more efficient hybrid systems for batteries, electronic devices or applications in catalysis.
2D-PnictoChem project can be categorized in 4 objectives (WPs): i) Production/exfoliation of thin layer pnictogens; ii) Chemical functionalization by means of non-covalent and covalent approaches; iii) Development of hybrid architectures; and iv) 2D-Pnictogens Applications. Since the beginning of the project, we have intensively worked mainly in WPs1&2, but certainly, we have advanced all WPs. The work performed in 2D-PnictoChem can be grouped around three classes of materials/devices: i) 2D-Pnictogens nanomaterials (phosphorene, antimonene, and bismuthene); ii) Hybrid architectures (these include, among others, the combination of 2D-Pnictogens with other nanomaterials such as graphene or layered hydroxides); iii) Devices and 2D nanocomposite materials.
Related with the first class of materials we have obtained new 2D materials based on black phosphorus, antimony, bismuth, layered double hydroxides (LDHs) and graphene using different approaches such as liquid phase exfoliation, micromechanical exfoliation and chemical synthesis. A major achievement has been the bottom-up large-scale colloidal synthesis of antimonene hexagons (AH). Indeed, our optimized synthesis yields AH with lateral dimensions up to 6 microns and thicknesses in between 4 and 20 nm, comparable to those made using chemical vapor deposition or molecular beam epitaxy (MBE). Last but not least, we have been able to demonstrate the high quality (and low degree of surface oxidation) of these AH by means of mechanical and transport experiments. This major achievement provides an alternative preparation route for high-quality antimonene with the higher yields reported to date. Even more, we have deciphered the oxidation behaviour in antimonene, controlling the formation of antimonene oxide/antimonene heterostructures. Finally, extremely interesting results have been achieved with bismuthene, which are being patented and will soon be published. These results open the door for the development of heavy pnictogens-based technologies since it allows for the first time the large-scale synthesis of high-quality nanosheets for applications in electronics and beyond.
Related with the second class of materials, a breakthrough has been the first bulk reductive covalent functionalization of black phosphorus, which lead to the highest functionalization degrees reported to date, as well as revealed the P–P bond breakage that takes place after the functionalization. Moreover, it has been possible to quantify for the first time the covalent functionalization of black phosphorus by means of Raman spectroscopy. In order to carry out hybrid heterostructures, we have developed an enormous work of synthesis of other functionalized 2D materials. As a matter of fact, we developed the first covalent functionalization of NiFe LDHs, a layered material of great interest in energy transformation, as well as the first bottom-up synthesis of ultrathin layered hexagonal magnets based on α-CoII hydroxychlorides. Moreover, we carried out the first multifunctionalization of high-quality graphene with 3 different protected functional groups that pave the way for the ulterior post-functionalization. Altogether we are in a privileged position to face the preparation of hybrid heterostructures assembled by different interface interactions (and not only van der Waals forces).
With respect to the third class of materials (devices and 2D nanocomposites), one major breakthrough has been the first use of 2D-Pnictogens in organic catalysis. Specifically, we have developed the liquid phase exfoliation of phosphorene and antimonene in ionic liquids leading to completely unoxidized layers that behave as excellent catalysts in the alkylation of soft nucleophiles with esters. In terms of electronic devices, a major achievement has been the preparation of the first organic field-effect transistor with functionalized black phosphorus through the non-covalent pathway with ad-hoc synthesized perylenes. Another major achievement has been the preparation, using a molecular approach, of nanocomposites formed by graphene and magnetic nanoparticles exhibiting unparalleled supercapacitive properties in the presence of an external magnetic field resulting in a giant enhancement of the capacitance.
Related with the first class of materials we have obtained new 2D materials based on black phosphorus, antimony, bismuth, layered double hydroxides (LDHs) and graphene using different approaches such as liquid phase exfoliation, micromechanical exfoliation and chemical synthesis. A major achievement has been the bottom-up large-scale colloidal synthesis of antimonene hexagons (AH). Indeed, our optimized synthesis yields AH with lateral dimensions up to 6 microns and thicknesses in between 4 and 20 nm, comparable to those made using chemical vapor deposition or molecular beam epitaxy (MBE). Last but not least, we have been able to demonstrate the high quality (and low degree of surface oxidation) of these AH by means of mechanical and transport experiments. This major achievement provides an alternative preparation route for high-quality antimonene with the higher yields reported to date. Even more, we have deciphered the oxidation behaviour in antimonene, controlling the formation of antimonene oxide/antimonene heterostructures. Finally, extremely interesting results have been achieved with bismuthene, which are being patented and will soon be published. These results open the door for the development of heavy pnictogens-based technologies since it allows for the first time the large-scale synthesis of high-quality nanosheets for applications in electronics and beyond.
Related with the second class of materials, a breakthrough has been the first bulk reductive covalent functionalization of black phosphorus, which lead to the highest functionalization degrees reported to date, as well as revealed the P–P bond breakage that takes place after the functionalization. Moreover, it has been possible to quantify for the first time the covalent functionalization of black phosphorus by means of Raman spectroscopy. In order to carry out hybrid heterostructures, we have developed an enormous work of synthesis of other functionalized 2D materials. As a matter of fact, we developed the first covalent functionalization of NiFe LDHs, a layered material of great interest in energy transformation, as well as the first bottom-up synthesis of ultrathin layered hexagonal magnets based on α-CoII hydroxychlorides. Moreover, we carried out the first multifunctionalization of high-quality graphene with 3 different protected functional groups that pave the way for the ulterior post-functionalization. Altogether we are in a privileged position to face the preparation of hybrid heterostructures assembled by different interface interactions (and not only van der Waals forces).
With respect to the third class of materials (devices and 2D nanocomposites), one major breakthrough has been the first use of 2D-Pnictogens in organic catalysis. Specifically, we have developed the liquid phase exfoliation of phosphorene and antimonene in ionic liquids leading to completely unoxidized layers that behave as excellent catalysts in the alkylation of soft nucleophiles with esters. In terms of electronic devices, a major achievement has been the preparation of the first organic field-effect transistor with functionalized black phosphorus through the non-covalent pathway with ad-hoc synthesized perylenes. Another major achievement has been the preparation, using a molecular approach, of nanocomposites formed by graphene and magnetic nanoparticles exhibiting unparalleled supercapacitive properties in the presence of an external magnetic field resulting in a giant enhancement of the capacitance.
Most of the results obtained in 2D-PnictoChem so far are beyond the current state-of-the-art. Just to mention a few, we can consider i) large-scale colloidal synthesis of few-layer 2D-pnictogens with electronic quality; ii) discovery of the oxidation behavior in antimonene and characterization of the bandgap; iii) first bulk covalent functionalization of phosphorene and the quantification of the functionalization degree; iv) first organic field effect transistor using a 2D-pnictogen; v) first use of 2D-Pnictogens in organic catalysis of industrial relevance; vi) the preparation of 2D magnetic nanocomposites that respond to a magnetic stimulus to enhance their supercapacitive properties.
From now on and until the end of the project, we plan to extend the results obtained, achieving several major breakthroughs:
i) Synthesis of bismuthene with controlled allotropy and interphase functionalization.
ii) Developing electronics and plasmonics on antimonene and bismuthene.
iii) Extending the non-covalent and covalent functionalization to antimonene and bismuthene hexagons.
iv) Preparation of novel heterostructures based on Pnictogens using wet chemistry.
v) Search for novel stimuli-responsive hybrid heterostructures of interest in electronics and magnetism.
vi) Preparation and processing of hybrid 2D-pnictogens for applications in energy storage & conversion and catalysis.
From now on and until the end of the project, we plan to extend the results obtained, achieving several major breakthroughs:
i) Synthesis of bismuthene with controlled allotropy and interphase functionalization.
ii) Developing electronics and plasmonics on antimonene and bismuthene.
iii) Extending the non-covalent and covalent functionalization to antimonene and bismuthene hexagons.
iv) Preparation of novel heterostructures based on Pnictogens using wet chemistry.
v) Search for novel stimuli-responsive hybrid heterostructures of interest in electronics and magnetism.
vi) Preparation and processing of hybrid 2D-pnictogens for applications in energy storage & conversion and catalysis.