2D materials shows great promise for use in flexible electronics because their atomic thickness allows for maximum electrostatic control, optical transparency, sensitivity and mechanical flexibility. In addition, different 2D crystals can be easily combined in one stack, offering unprecedented control on the performance and functionalities of the resulting heterostructure device [3]. Solution processing of 2D materials allows simple and low-cost techniques, such as ink-jet printing, to be used for fabrication of heterostructure-based devices of arbitrary complexity.

Our group has developed highly concentrated, defect-free, biocompatible and inkjet printable and water-based 2D crystal formulations, by exploiting a supramolecular approach based on non-covalent functionalization of 2D materials with pyrene derivatives [1]. Examples of printed heterostructures, such as arrays of photosensors, programmable logic memories, transistors and memristors will be discussed [2-3]. I will show that inkjet printing can be easily combined with semiconducting 2D materials produced by chemical vapor deposition, allowing simple and quick fabrication of complex circuits on paper, compatible with CMOS technology [4-5] and also offers a simple way to integrate 2D materials into Si-based technology [6].

In contrast to the tremendous efforts dedicated to the exploration of graphene and inorganic 2D crystals such as metal dichalcogenides, boron nitride, black phosphorus, metal oxides, and nitrides, there has been much less development in organic 2D crystalline materials, including the bottom-up organic/polymer synthesis of graphene nanoribbons, 2D metal-organic frameworks, 2D polymers/supramolecular polymers, as well as the supramolecular approach to 2D organic nanostructures. One of the central chemical challenges is to realize a controlled polymerization in two distinct dimensions under thermodynamic/kinetic control in solution and at the surface/interface. In this talk, we will present our recent efforts in bottom-up synthetic approaches toward novel organic 2D crystals with structural control at the atomic/molecular level. On-water surface synthesis provides a powerful synthetic platform by exploiting surface confinement and enhanced chemical reactivity and selectivity. We will particularly present a surfactant-monolayer assisted interfacial synthesis (SMAIS) method that is highly efficient in promoting the programmable assembly of precursor monomers on the water surface and subsequent 2D polymerization in a controlled manner. 2D conjugated polymers and coordination polymers belong to such material classes. The unique 2D crystal structures with possible tailoring of conjugated building blocks and conjugation lengths, tunable pore sizes and thicknesses, as well as impressive electronic structures, make them highly promising for a range of applications in electronics, optoelectronics, and spintronics. Other physicochemical phenomena and application potential of organic 2D crystals, such as in membranes, will also be discussed.

The last few years have seen the increasing occurrence of water contamination by pharmaceuticals, personal care products, plastic and their additives among the other,^1-5 that are not satisfyingly removed by conventional drinking water treatment technologies.^{6, 7} In some cases, as for the endocrine disrupting agents such as per and polyfluoroalkyl substances (PFAS) and bisphenol A (BPA), the eco and human toxicity has been demonstrated ^8-11 calling for the urgent development of new technologies for detection, early warning and remediation of such  emerging contaminants.

Due to its commercial availability at good standard quality and processability in composite or membranes, graphene is one of the most promising nanomaterials for the realization of new technologies for water purification. In this talk,  I will present a selection of case studies of graphene-and chemically modified based materials and devices realized at CNR to detect and remove emerging contaminants including pharmaceuticals, personal care products and PFAS), from drinking water.[1,2,3] I will discuss about performance, sustainability issues in comparison with standard technologies and future challenges to respond to the sustainable development goal n6 of the UN ‘ensuring clean water and sanitation to all’.

The synthesis of different hydrophilic polymeric networks, by in situ radical polymerization in the presence of 2D materials, gives rise to three-dimensional soft structures. The role of the nanomaterial within the polymeric network is mainly intended for reinforcement (i.e. stiffness and toughness enhancement). However, we have shown that the presence of 2D materials, such as graphene, can also enhance features such as biocompatibility [1], sensing [2] or self-healing capability [3], giving rise to truly hybrid composites [4]. Moreover, the ability of these soft materials to respond to different stimuli, such as electric and magnetic fields, to behave as sensors, and the possibility to prepare them following 3D printing methodologies, open the way to applications in soft robotics [5]. The preparation of these smart soft systems requires the production of large quantities of 2D materials easily dispersible in water; ball milling methods developed in our laboratories have proven to be both sustainable and easily scalable technologies. [6], [7].

This talk aims to show the latest advances we have made on two-dimensional (2D) materials for energy storage and conversion. Specifically, we will show the great promise of a disruptive family of 2D transition metal layered hydroxides (LH), which exhibit a wide chemical tunability and can be produced in large scale. Indeed, a series of single and layered double hydroxides will be discussed including the Simonkolleite phases of cobalt-LH or the NiFe-LDHs of great interest in electrocatalysis, or the hybrid organic-inorganic LDHs of interest as precursors for the preparation of electrodes for rechargable alkaline batteries. Along with their synthesis and characterization, we will show the performance of these wonderful materials in the development of new battery prototypes or better electrocatalysts for the production of green hydrogen. Last but not least, we will show a new family of hybrid 2D-LHs with great potential as electrode materials: the so-called "meta-layered hydroxides".

A precise knowledge of the optical and electrical properties of 2D nanomaterials, is essential for pushing forward these materials in energy applications. In this regard, synthesis and studies of nanohybrids at single-crystal scale is a promising alternative to study the intrinsic properties of a photoactive material, since it is avoided the effect of the grain boundaries and amorphous domains present in polycrystalline films using for that purpose a homemade setup. [1, 2]

In this communication, we present the optical study of different microstructured materials such as hybrid perovskites for the development materials with applications in the field of energy conversion, optoelectronics and lighting. For instance, the incorporation of SubPc in the interlayer space of 2D–3D perovskites expands the photoresponse in the visible region [3]. SubPc incorporation was achieved by selectively controlling the composition during the synthesis. Photocurrent spectra on isolated single crystals indicates that SubPc molecules are participating in the charge generation process upon illumination, and acts as light harvester for long wavelength radiations. All these studies provide relevant information for device manufacturing in the development of high-efficiency solar cells, photocatalysts and optoelectronic devices. [1-4]

Heterogeneous photocatalysis by readily available, metal-free catalysts is of great appeal in view of the increasing pressure on industry to move towards sustainable schemes of chemical production. Graphitic carbon nitride (g-CN) is a versatile semiconductor nanomaterial, well known for applications in energy, such as H₂ photocatalytic production and CO₂ reduction. We recently highlighted the key role that g-CN could play in the realm of photocatalytic organic synthesis, [1] and showed that tailoring the structure of g-CN by means of minimally invasive post-synthetic protocols could be the solution to tackle challenging coupling reactions with great efficiency.[2,3] Through international collaborations, our group embarked in the in depth investigation of the structure/activity relationship of new g-CN derivatives related to photocatalysis, by means of a combination of advanced spectroscopic techniques [4] and computational methods.[5] The final goal is aims at establishing an approach based on rational design of modified CN materials, with properties tailored to the specific photocatalytic process. Apart from the strict metal-free photocatalysis, an additional possibility arises from the inclusion of single metal atoms into the CN scaffold, whereby the opportunely adjusted CN structure can interact and be in synergy with the metal site. This can be of high relevance both in dual photoredox catalysis for organic synthesis and in energy conversion processes.

In recent years, a plethora of material systems have been designed and prepared to increase the performance of light harvesting and light-emitting technologies, and to develop new and attractive applications. Limitations of state-of-the-art devices based on organics (both conjugated polymers or small molecules/oligomers) derive largely from material stability issues after prolonged operation. This challenge could be tackled by leveraging the enhanced stability of carbon nanostructures (CNSs, including carbon nanotubes and the large family of graphenebased materials) in carefully designed nano-hybrid or nano-composite architectures to be integrated within photo-active layers, paving the way to the exploitation of these materials in contexts in which their potential has not been yet fully revealed. In this talk, I will discuss the theoretical background behind CNSs hybridization with other materials such as graphene with donor-acceptor molecules, for the establishment of novel optoelectronic properties and provide an overview of new optoelectronic and transfer properties of twisted graphene nanoribbons with controlled peripheral size that allow to forecast interesting future perspectives for use in real devices.

Since the first discovery of graphene by Novoselov in 2004, graphene and in general 2D materials showed an increasing interest in the scientific community. Specifically Transition Metal Dichalcogenides (TMDC) showed a surge in interest, due to their different properties and flexibility due to the large amount of variability in the group. Not only this, but they can be easily engineered in different ways to tune their properties, examples are doping, functionalization and hybridation with other material¹. In this last context, Conductive Polymers (CP)² show complementary electrochemical properties to the 2D TMDC materials and can be exploited to further improve their performances. Here, we report on the synthesis of hybrids based polyaniline (PANI) and 2D transition metal dichalcogenides (TMDCs), employing different methodologies and formulations. In particular, we resort to liquid phase exfoliation (LPE)³ to produce 2D TMDCs in both the 2H and 1T phase and to in-situ polymerization to produce PANI chains directly on the surface of these nanomaterials to further amplify the electrochemical properties of the 2D material. Then the as obtained material can be further characterized electrochemically and can be also used in conjunction with flexible polymer scaffold in order to obtain piezo- active hydrogels. The as-obtained hydrogels are characterized through a combination of techniques and their swelling behaviour and mechanical properties are investigated.

Due to their outstanding electronic, thermal, optical, chemical, and mechanical properties, 0/1/2D carbon nanostructures (CNSs) have attracted great interest in the last two decades.^[1] Among CNSs, different procedures have been developed to synthesize carbon nanodots (CNDs) starting from a large pool of small molecules through a bottom-up approach, and several applications for these nanomaterials have been investigated.^[2,3] CNDs can be further decorated through chemical functionalization for sensing, catalysis, and optoelectronic applications. For example, light-conversion processes in covalently functionalized CNDs with donor-acceptor organic dyes can be investigated.^[4] Therefore, it is important to analyze the reactivity and accessibility of the surface functional groups, as well as their total quantities. This contribution discusses the characterization and quantification of the terminal functional groups of four different bottom-up synthesized CNDs.^[5] We resorted to pH back-titrations, Kaiser tests, X-ray photoelectron spectroscopy (XPS), and quantitative ¹⁹F-NMR of incorporated fluorine atoms to quantify the terminal amine content in the prepared CND samples. XPS provides both the surface functional group content and, together with elemental analysis (EA), the elemental composition of the synthesized CNDs. The amount of ethylene diamine used as starting material governs the fraction of functional groups on the surface. This quantification, before and after functionalization, provides useful information about the reactivity and accessibility of the terminal functional groups. Hereby, the yields of reactions can subsequently be determined. Based on the different amounts of terminal amino groups of these four CNDs, it is possible to determine which is most suitable for further functionalization.

Colloidal CdTe nanoplatelets featuring a large absorption coefficient and ultrafast tunable luminescence coupled with heavy-metal-based composition present themselves as highly desirable candidates for radiation detection technologies [1]. Historically, however, these nanoplatelets have suffered from poor emission efficiency, hindering progress in exploring their technological potential [2], [3]. In this talk, we report the synthesis of CdTe nanoplatelets possessing a record emission efficiency of 9%. This enables us to investigate their fundamental photophysics using ultrafast transient absorption, temperature-controlled photoluminescence, and radioluminescence measurements, elucidating the origins of exciton- and defect-related phenomena under both optical and ionizing excitation. For the first time in CdTe nanoplatelets, in this talk is reported the cumulative effects of a giant oscillator strength transition (GOST) and exciton fine structure. Simultaneously, thermally stimulated luminescence measurements reveal the presence of both shallow and deep trap states and allow us to disclose the trapping and detrapping dynamics and their influence on the scintillation properties [4].

Silver phenylselenolate (AgSePh) and silver phenyltellurolate (AgTePh) are novel two-dimensional (2D) van der Waals semiconductors. In contrast to 2D layered perovskites and transition metal dichalcogenides, AgSePh and AgTePh have strong covalent interaction between organic and inorganic components, becoming truly hybrid organic-inorganic semiconductors. However, despite having the similar crystal structure, composition and absorption characteristics, AgSePh and AgTePh exhibit strikingly different light emission characteristics. Whereas AgSePh exhibit narrow, fast luminescence with a minimal Stokes shift that tracks the temperature-dependent shifting of the lowest-energy excitonic absorption resonance, AgTePh exhibits comparatively slow, significantly broadened luminescence with large Stokes shift that does not track the shifting of excitonic absorption resonance peak with changing temperature. In this presentation, we will present the synthesis, structure and excitonic optical properties of AgSePh and AgTePh films. Furthermore, we will discuss different physical mechanisms underlying light emission in AgSePh and AgTePh. Using time-resolved and temperature-dependent optical spectroscopy, combined with sub-gap photoexcitation spectroscopy, we will show that exciton dynamics in AgTePh are dominated by intrinsic self-trapping behavior, whereas dynamics in AgTePh are dominated by interaction of band edge excitons with extrinsic defect states. Finally, we will show tunable excitonic properties in AgSe_1-xTe_xPh alloys depending on composition.

Two-dimensional (2D) materials can provide a suitable platform to develop new technologies for energy applications. In my group we are combining functional molecules with 2D materials with the idea of tuning/improving the properties of the “all surface” 2D material via an active control of the hybrid interface. This concept, which goes much beyond the conventional chemical functionalization of a 2D material, can provide an entire new class of hybrid molecular / 2D heterostructures, which may be at the origin of a novel generation of materials and devices of direct application in electronics, spintronics, molecular sensing and energy. Here this concept will be presented and used in the design of low energy consumption spintronic devices as well as in energy storage and conversion. In the first part I will show that 2D magnetic materials as well as hybrid molecular /2D antiferromagnets can be used to store and transport information with extremely low energy disipation and tunability. In the second part, hybrid materials formed by electroactive inorganic layers will be used as electrodes in supercapacitive devices and as electrocatalysts.

Photovoltaic and solar fuels technologies rely upon the intentional movement of charge carriers (i.e. electrons and holes) and/or energy (i.e. excitons) in prescribed directions to convert sunlight into electricity or fuels. Two-dimensional semiconductors have several advantages for PV and (photo)catalytic technologies, due to their large absorption coefficients, high mobilities for charge carriers and excitons, and catalytic activity for important fuel-forming reactions. To realize the full potential of 2D nanomaterials and related heterostructures for sustainable energy technologies, fundamental studies are needed to probe the key photochemical processes that occur upon photon absorption, including exciton diffusion and dissociation, interfacial charge and energy transfer, and charge recombination. In this presentation, I will highlight our ongoing studies probing charge and energy transfer across heterojunctions formed between monolayer transition metal dichalcogenides (TMDCs) and other nanoscale semiconductors such as semiconducting single-walled carbon nanotubes, small molecules, and nanocrystals. Appropriate tuning of the interfacial band alignment can enable rapid exciton dissociation and exceptionally long-lived charge-separated states that are essential for PV and catalytic applications. Tuning the binding motif of molecular species between van der Waals association and covalent bonds can also influence the mechanisms of interfacial charge/energy transfer. If time permits, I will also discuss how certain 2D nanomaterials can facilitate charge/energy transfer while simultaneously blocking undesired ion movement across the heterojunction.

2D organic semiconducting polymers have emerged as an important class of materials that offer high potential for a variety of applications, such as energy storage, sensing or organic electronics. However, the design of novel materials generally involves an expensive and environmentally unfriendly methodology that strongly contrasts with the ecological transition spirit. In this sense, computational design offers a green alternative to experimental laboratory research. On the other hand, Raman spectroscopy is a fast and nondestructive characterization tool widely used to evaluate the structural and electronic properties of pi-conjugated materials. In this study, we combine an experimental and theoretical approach that links DFT calculations with Raman spectroscopy aiming to control the electronic and structural properties of conjugated organic materials  Overall, our findings open the door to the control of the degree of the π-conjugation of 2D organic polymers for their subsequent synthesis and real applications ranging from sensing to electronics.