The discovery of graphene, with its unique properties, has inspired the quest for other two-dimensional (2D) materials. After considerable research efforts by the scientific community in the last 15 years, an extended atlas of 2D materials has been synthetized and investigated. Remarkably, materials beyond graphene could possess properties complementary to those of graphene, such as the presence of a direct band gap, more suitable for several applications, not limited to nano- and opto-electronics. Moreover, these materials have high potential for applications in biosensing technologies, catalysis, photocatalysis and energy storage. However, considering that most 2D materials have been newly discovered, the majority of the research efforts is focused on material synthesis and on the investigation of its electronic properties. Therefore, technological applications of 2D materials are still at the embryonic stage, also considering the difficulties in achieving large-scale and low-cost production for industrial use. Among the various 2D materials, graphene-based derivatives and metal chalcogenides represent the most promising materials for technological applications. Graphene oxide (GO) has attracted particular attention from the industrial world, since it represents a low-cost precursor of graphene for large-scale production. GO offers tremendous opportunities for the access to functionalized graphene‐based materials. More specifically, both GO and reduced GO (rGO) can be processed into a wide variety of novel materials with distinctly different morphological features, where the carbonaceous nanosheets can serve as either the sole component, as in papers and thin films, or as fillers in polymer and/or inorganic nanocomposites. In addition, GO and rGO enable efficient electro-optical, filtering and nano-biotechnological applications, as well as gas sensing devices, polymeric nanocomposites and gas barriers. On the other hand, transition-metal dichalcogenides (TMDs) belonging to the class of MTe2 (M = Ni, Pd) are particularly relevant for both fundamental and technological interest, owing to the presence of a tilted Dirac cone formed by bulk states, which implies high-mobility charge carriers. Being the Dirac cone located in the bulk, it naturally exhibits superior robustness to surface modifications compared to other Dirac materials, i.e. graphene, topological insulators and silicene. Consequently, MTe2 displays intriguing application capabilities in optoelectronics and catalysis, in consideration of its nature as type-II Dirac semimetal. In addition, among the broad class of layered metal chalcogenides, van der Waals semiconductors are particularly suitable for optoelectronic and sensing devices. Especially, recent experiments on exfoliated GaSe nanosheets reported an enhancement of performance in electrochemistry and photocatalysis opening a new way for its applications in the fields of energy and catalysis. In addition, SnSe2 represent another interesting van der Waals semiconductor with ultralow thermal conductivity. In this thesis, issues related to technology transfer of 2D materials beyond graphene were addressed. More specifically, a solution for the reduction of costs in the state-of-the-art production of GO was identified. Moreover, a sustainable eco-friendly solvent was demonstrated to be able to replace toxic solvents in the large-scale production of functional inks based on 2D materials, solving one of the most relevant problems for the 2D materials-based industry.

Sintesi, Funzionalizzazione e Caratterizzazione di Materiali Bidimensionali Avanzati / D'Olimpio, Gianluca. - (2021 May 21).

Sintesi, Funzionalizzazione e Caratterizzazione di Materiali Bidimensionali Avanzati

D'OLIMPIO, GIANLUCA
2021

Abstract

The discovery of graphene, with its unique properties, has inspired the quest for other two-dimensional (2D) materials. After considerable research efforts by the scientific community in the last 15 years, an extended atlas of 2D materials has been synthetized and investigated. Remarkably, materials beyond graphene could possess properties complementary to those of graphene, such as the presence of a direct band gap, more suitable for several applications, not limited to nano- and opto-electronics. Moreover, these materials have high potential for applications in biosensing technologies, catalysis, photocatalysis and energy storage. However, considering that most 2D materials have been newly discovered, the majority of the research efforts is focused on material synthesis and on the investigation of its electronic properties. Therefore, technological applications of 2D materials are still at the embryonic stage, also considering the difficulties in achieving large-scale and low-cost production for industrial use. Among the various 2D materials, graphene-based derivatives and metal chalcogenides represent the most promising materials for technological applications. Graphene oxide (GO) has attracted particular attention from the industrial world, since it represents a low-cost precursor of graphene for large-scale production. GO offers tremendous opportunities for the access to functionalized graphene‐based materials. More specifically, both GO and reduced GO (rGO) can be processed into a wide variety of novel materials with distinctly different morphological features, where the carbonaceous nanosheets can serve as either the sole component, as in papers and thin films, or as fillers in polymer and/or inorganic nanocomposites. In addition, GO and rGO enable efficient electro-optical, filtering and nano-biotechnological applications, as well as gas sensing devices, polymeric nanocomposites and gas barriers. On the other hand, transition-metal dichalcogenides (TMDs) belonging to the class of MTe2 (M = Ni, Pd) are particularly relevant for both fundamental and technological interest, owing to the presence of a tilted Dirac cone formed by bulk states, which implies high-mobility charge carriers. Being the Dirac cone located in the bulk, it naturally exhibits superior robustness to surface modifications compared to other Dirac materials, i.e. graphene, topological insulators and silicene. Consequently, MTe2 displays intriguing application capabilities in optoelectronics and catalysis, in consideration of its nature as type-II Dirac semimetal. In addition, among the broad class of layered metal chalcogenides, van der Waals semiconductors are particularly suitable for optoelectronic and sensing devices. Especially, recent experiments on exfoliated GaSe nanosheets reported an enhancement of performance in electrochemistry and photocatalysis opening a new way for its applications in the fields of energy and catalysis. In addition, SnSe2 represent another interesting van der Waals semiconductor with ultralow thermal conductivity. In this thesis, issues related to technology transfer of 2D materials beyond graphene were addressed. More specifically, a solution for the reduction of costs in the state-of-the-art production of GO was identified. Moreover, a sustainable eco-friendly solvent was demonstrated to be able to replace toxic solvents in the large-scale production of functional inks based on 2D materials, solving one of the most relevant problems for the 2D materials-based industry.
Sintesi, Funzionalizzazione e Caratterizzazione di Materiali Bidimensionali Avanzati / D'Olimpio, Gianluca. - (2021 May 21).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11697/168999
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