Francesca Alessandro - Academia.edu (original) (raw)
Papers by Francesca Alessandro
Membranes, Feb 21, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Chemistry, Jan 2, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Desalination, Nov 1, 2023
Journal of Membrane Science, Sep 1, 2022
Chemistry
Sustainable water desalination and purification membrane processes require new practical pathways... more Sustainable water desalination and purification membrane processes require new practical pathways to improve their efficiency. To this end, the inclusion of two-dimensional materials in membrane structure has proven to have a significant impact in various applications. In particular, in processes such as membrane distillation and crystallization, these materials, thanks to their characteristics, help to increase the recovery of clean water and, at the same time, to improve the quality and the production of the recovered salts. Therefore, a fundamental aspect of obtaining 2D materials with certain characteristics is the technique used for the preparation. This review provides a broad discussion on the preparation and proprieties of 2D materials, including examples of organic structures (such as graphene and structures containing transition metals and organic metals). Finally, the critical challenges, future research directions, and the opportunities for developing advanced membranes ...
ACS Applied Nano Materials
Compared to artificial metamaterials, where nano-fabrication complexities and finite-size inclusi... more Compared to artificial metamaterials, where nano-fabrication complexities and finite-size inclusions can hamper the desired electromagnetic response, several natural materials like van der Waals crystals hold great promise for designing efficient nanophotonic devices in the optical range. Here, we investigate the unusual optical response of NiTe2, a van der Waals crystal and a type-II Dirac semimetal hosting Lorentz-violating Dirac fermions. By ab initio density functional theory modeling, we show that NiTe2 harbors multiple topological photonic regimes for evanescent waves (such as surface plasmons) across the near-infrared and optical range. By electron energy-loss experiments, we identify surface plasmon resonances near the photonic topological transition points at the epsilon-near-zero (ENZ) frequencies ≈ 0.79, 1.64, and 2.22 eV. Driven by the extreme crystal anisotropy and the presence of Lorentz-violating Dirac fermions, the experimental evidence of ENZ surface plasmon resonances confirm the non-trivial photonic and electronic topology of NiTe2. Our study paves the way for realizing devices for light manipulation at the deep-subwavelength scales based on electronic and photonic topological physics for nanophotonics, optoelectronics, imaging, and biosensing applications.
Membranes
Water scarcity raises important concerns with respect to human sustainability and the preservatio... more Water scarcity raises important concerns with respect to human sustainability and the preservation of important ecosystem functions. To satisfy water requirements, seawater desalination represents one of the most sustainable solutions. In recent decades, membrane distillation has emerged as a promising thermal desalination process that may help to overcome the drawbacks of traditional desalination processes. Nevertheless, in membrane distillation, the temperature at the feed membrane interface is significantly lower than that of the bulk feed water, due to the latent heat flux associated with water evaporation. This phenomenon, known as temperature polarization, in membrane distillation is a crucial issue that could be responsible for a decay of about 50% in the initial transmembrane water flux. The use of plasmonic nanostructures, acting as thermal hotspots in the conventional membranes, may improve the performance of membrane distillation units by reducing or eliminating the tempe...
ACS Applied Nano Materials
Compared to artificial metamaterials, where nano-fabrication complexities and finite-size inclusi... more Compared to artificial metamaterials, where nano-fabrication complexities and finite-size inclusions can hamper the desired electromagnetic response, several natural materials like van der Waals crystals hold great promise for designing efficient nanophotonic devices in the optical range. Here, we investigate the unusual optical response of NiTe2, a van der Waals crystal and a type-II Dirac semimetal hosting Lorentz-violating Dirac fermions. By ab initio density functional theory modeling, we show that NiTe2 harbors multiple topological photonic regimes for evanescent waves (such as surface plasmons) across the near-infrared and optical range. By electron energy-loss experiments, we identify surface plasmon resonances near the photonic topological transition points at the epsilon-near-zero (ENZ) frequencies ≈ 0.79, 1.64, and 2.22 eV. Driven by the extreme crystal anisotropy and the presence of Lorentz-violating Dirac fermions, the experimental evidence of ENZ surface plasmon resonances confirm the non-trivial photonic and electronic topology of NiTe2. Our study paves the way for realizing devices for light manipulation at the deep-subwavelength scales based on electronic and photonic topological physics for nanophotonics, optoelectronics, imaging, and biosensing applications.
Chemistry
In recent decades, membrane-based processes have been extensively applied to a wide range of indu... more In recent decades, membrane-based processes have been extensively applied to a wide range of industrial processes, including gas separation, food industry, drug purification, and wastewater treatment. Membrane distillation is a thermally driven separation process, in which only vapour molecules transfer through a microporous hydrophobic membrane. At the operational level, the performance of membrane distillation is negatively affected by wetting and temperature polarization phenomena. In order to overcome these issues, advanced membranes have been developed in recent years. This review, which focuses specifically on membrane distillation presents the basic concepts associated with the mass and heat transfer through hydrophobic membranes, membrane properties, and advances in membrane materials. Photothermal materials for solar-driven membrane distillation applications are also presented and discussed.
Physical Review B, 2018
Silicene, the two-dimensional allotrope of silicon, is predicted to exist in a low-buckled honeyc... more Silicene, the two-dimensional allotrope of silicon, is predicted to exist in a low-buckled honeycomb lattice, characterized by semimetallic electronic bands with graphenelike energy-momentum dispersions around the Fermi level (represented by touching Dirac cones). Single layers of silicene are mostly synthesized by depositing silicon on top of silver, where, however, the different phases observed to date are so strongly hybridized with the substrate that not only the Dirac cones, but also the whole valence and conduction states of ideal silicene appear to be lost. Here, we provide evidence that at least part of this semimetallic behavior is preserved by the coexistence of more silicene phases, epitaxially grown on Ag(111). In particular, we combine electron energy loss spectroscopy and time-dependent density functional theory to characterize the low-energy plasmon of a multiphase-silicene/Ag(111) sample, prepared at controlled silicon coverage and growth temperature. We find that this mode survives the interaction with the substrate, being perfectly matched with the π-like plasmon of ideal silicene. We therefore suggest that the weakened interaction of multiphase silicene with the substrate may provide a unique platform with the potential to develop novel applications based on two-dimensional silicon systems.
Nanomaterials, 2020
Porous carbon materials are currently subjected to strong research efforts mainly due to their ex... more Porous carbon materials are currently subjected to strong research efforts mainly due to their excellent performances in energy storage devices. A sustainable process to obtain them is hydrothermal carbonization (HTC), in which the decomposition of biomass precursors generates solid products called hydrochars, together with liquid and gaseous products. Hydrochars have a high C content and are rich with oxygen-containing functional groups, which is important for subsequent activation. Orange pomace and orange peels are considered wastes and then have been investigated as possible feedstocks for hydrochars production. On the contrary, orange juice was treated by HTC only to obtain carbon quantum dots. In the present study, pure orange juice was hydrothermally carbonized and the resulting hydrochar was filtered and washed, and graphitized/activated by KOH in nitrogen atmosphere at 800 °C. The resulting material was studied by transmission and scanning electron microscopy, Raman spectro...
Applied Surface Science, 2021
Abstract The electronic properties of graphite with rotational stacking faults are strongly modif... more Abstract The electronic properties of graphite with rotational stacking faults are strongly modified with respect to Bernal-stacked graphite, with the recovery of the Dirac cones for sufficiently high misorientation angles. A particular case is represented by twisted bilayer graphene (TBLG), in which twist angles are univocally related to the frequency of rotation modes observed in Raman spectra. The electronic properties determined by Dirac fermions make highly desirable to develop simple routes to synthesize highly decoupled turbostratic graphite and TBLG, as an alternative to single-layer graphene (SLG) for graphene-based electronic devices. In this work, we present a synthesis of hollow iron microspheres wrapped by graphitic layers in water-submerged arc discharge experiments between graphite electrodes, with an iron wire inserted into the anode. The microspheres were studied by scanning electron microscopy, microprobe energy-dispersive X-ray spectroscopy and Raman spectroscopy. We observed domains showing rotation and combination Raman modes typical of TBLG with different rotation angles, together with domains made of turbostratic graphite. The twist angles found in TBLG domains are indicative of values of the Fermi velocity close to the value of SLG. Our results open a new road for the synthesis of robust graphitic materials with the electronic properties of SLG.
Physical Review B, 2019
We explore the broadband excitation spectrum of bulk PtTe2 using electron energy loss spectroscop... more We explore the broadband excitation spectrum of bulk PtTe2 using electron energy loss spectroscopy and density functional theory. In addition to infrared modes related to intraband 3D Dirac plasmon and interband transitions between the 3D Dirac bands, we observe modes at 3.9, 7.5 and 19.0 eV in the ultraviolet region. The comparison of the excitation spectrum with the calculated orbital-resolved density of states allows us to ascribe spectral features to transitions between specific electronic states. Additionally, we study the thickness dependence of the high-energy plasmon in the PtTe2 thin films. We show that, unlike graphene, the high-energy plasmon in PtTe2 thin film gets red-shifted by ∼2.5 eV with increasing thickness.
Nanomaterials
Reduced graphene oxide (rGO) is one of the most well-known graphene derivatives, which, due to it... more Reduced graphene oxide (rGO) is one of the most well-known graphene derivatives, which, due to its outstanding physical and chemical properties as well as its oxygen content, has been used for wastewater treatment technologies. Particularly, extra functionalized rGO is widely preferred for treating wastewater containing dyes or heavy metals. Nevertheless, the use of non-extra functionalized (pristine) rGO for the removal of cationic pollutants is not explored in detail or is ambiguous. Herein, pristine rGO—prepared by an eco-friendly protocol—is used for the removal of cationic pollutants from water, i.e., methylene blue (MB) and mercury-(II) (Hg-(II)). This work includes the eco-friendly synthesis process and related spectroscopical and morphological characterization. Most importantly, the investigated rGO shows an adsorption capacity of 121.95 mg g−1 for MB and 109.49 mg g−1 for Hg (II) at 298 K. A record adsorption time of 30 min was found for MB and 20 min for Hg (II) with an ef...
Carlo Rizza, ∗ Debasis Dutta, Barun Ghosh, 3 Francesca Alessandro, Chia-Nung Kuo, Chin Shan Lue, ... more Carlo Rizza, ∗ Debasis Dutta, Barun Ghosh, 3 Francesca Alessandro, Chia-Nung Kuo, Chin Shan Lue, Lorenzo S. Caputi, Arun Bansil, Amit Agarwal, Antonio Politano, 6, † and Anna Cupolillo Department of Physical and Chemical Sciences, University of L’Aquila, Via Vetoio 1, I-67100 L’Aquila, Italy Department of Physics, Indian Institute of Technology Kanpur, Kanpur-208016, India Department of Physics, Northeastern University, Boston, Massachusetts 02115, United States of America Department of Physics, University of Calabria, Via ponte Bucci, I-83036, Rende, Italy Department of Physics, National Cheng Kung University, 1 Ta-Hsueh Road 70101 Tainan, Taiwan CNR-IMM Istituto per la Microelettronica e Microsistemi, VIII strada 5, I-95121 Catania, Italy
Carbon nano-onions (CNOs), which consist of concentric graphitic shells, currently attract much a... more Carbon nano-onions (CNOs), which consist of concentric graphitic shells, currently attract much attention because of their unique structural and physical properties, which are different from the properties of the other carbon nanomaterials such as fullerenes, graphene, and carbon nanotubes (CNTs). Due to their small size, the large external surface area and high conductivity, CNOs are used for supercapacitor applications. The arc discharge underwater is an effective and simple method for the synthesis of larger CNOs in reasonable quantities. In this research, we have been obtained carbon nanomaterials using arc discharge in water between two high purity graphite electrodes. The main experimental techniques used to characterize carbon nanostructures have been Transmission Electron Microscopy (TEM) and Raman Spectroscopy. Among them, Raman spectroscopy is the most useful non-destructive technique capable of differentiating between these various structures. Our TEM images showed that t...
Membranes, Feb 21, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Chemistry, Jan 2, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Desalination, Nov 1, 2023
Journal of Membrane Science, Sep 1, 2022
Chemistry
Sustainable water desalination and purification membrane processes require new practical pathways... more Sustainable water desalination and purification membrane processes require new practical pathways to improve their efficiency. To this end, the inclusion of two-dimensional materials in membrane structure has proven to have a significant impact in various applications. In particular, in processes such as membrane distillation and crystallization, these materials, thanks to their characteristics, help to increase the recovery of clean water and, at the same time, to improve the quality and the production of the recovered salts. Therefore, a fundamental aspect of obtaining 2D materials with certain characteristics is the technique used for the preparation. This review provides a broad discussion on the preparation and proprieties of 2D materials, including examples of organic structures (such as graphene and structures containing transition metals and organic metals). Finally, the critical challenges, future research directions, and the opportunities for developing advanced membranes ...
ACS Applied Nano Materials
Compared to artificial metamaterials, where nano-fabrication complexities and finite-size inclusi... more Compared to artificial metamaterials, where nano-fabrication complexities and finite-size inclusions can hamper the desired electromagnetic response, several natural materials like van der Waals crystals hold great promise for designing efficient nanophotonic devices in the optical range. Here, we investigate the unusual optical response of NiTe2, a van der Waals crystal and a type-II Dirac semimetal hosting Lorentz-violating Dirac fermions. By ab initio density functional theory modeling, we show that NiTe2 harbors multiple topological photonic regimes for evanescent waves (such as surface plasmons) across the near-infrared and optical range. By electron energy-loss experiments, we identify surface plasmon resonances near the photonic topological transition points at the epsilon-near-zero (ENZ) frequencies ≈ 0.79, 1.64, and 2.22 eV. Driven by the extreme crystal anisotropy and the presence of Lorentz-violating Dirac fermions, the experimental evidence of ENZ surface plasmon resonances confirm the non-trivial photonic and electronic topology of NiTe2. Our study paves the way for realizing devices for light manipulation at the deep-subwavelength scales based on electronic and photonic topological physics for nanophotonics, optoelectronics, imaging, and biosensing applications.
Membranes
Water scarcity raises important concerns with respect to human sustainability and the preservatio... more Water scarcity raises important concerns with respect to human sustainability and the preservation of important ecosystem functions. To satisfy water requirements, seawater desalination represents one of the most sustainable solutions. In recent decades, membrane distillation has emerged as a promising thermal desalination process that may help to overcome the drawbacks of traditional desalination processes. Nevertheless, in membrane distillation, the temperature at the feed membrane interface is significantly lower than that of the bulk feed water, due to the latent heat flux associated with water evaporation. This phenomenon, known as temperature polarization, in membrane distillation is a crucial issue that could be responsible for a decay of about 50% in the initial transmembrane water flux. The use of plasmonic nanostructures, acting as thermal hotspots in the conventional membranes, may improve the performance of membrane distillation units by reducing or eliminating the tempe...
ACS Applied Nano Materials
Compared to artificial metamaterials, where nano-fabrication complexities and finite-size inclusi... more Compared to artificial metamaterials, where nano-fabrication complexities and finite-size inclusions can hamper the desired electromagnetic response, several natural materials like van der Waals crystals hold great promise for designing efficient nanophotonic devices in the optical range. Here, we investigate the unusual optical response of NiTe2, a van der Waals crystal and a type-II Dirac semimetal hosting Lorentz-violating Dirac fermions. By ab initio density functional theory modeling, we show that NiTe2 harbors multiple topological photonic regimes for evanescent waves (such as surface plasmons) across the near-infrared and optical range. By electron energy-loss experiments, we identify surface plasmon resonances near the photonic topological transition points at the epsilon-near-zero (ENZ) frequencies ≈ 0.79, 1.64, and 2.22 eV. Driven by the extreme crystal anisotropy and the presence of Lorentz-violating Dirac fermions, the experimental evidence of ENZ surface plasmon resonances confirm the non-trivial photonic and electronic topology of NiTe2. Our study paves the way for realizing devices for light manipulation at the deep-subwavelength scales based on electronic and photonic topological physics for nanophotonics, optoelectronics, imaging, and biosensing applications.
Chemistry
In recent decades, membrane-based processes have been extensively applied to a wide range of indu... more In recent decades, membrane-based processes have been extensively applied to a wide range of industrial processes, including gas separation, food industry, drug purification, and wastewater treatment. Membrane distillation is a thermally driven separation process, in which only vapour molecules transfer through a microporous hydrophobic membrane. At the operational level, the performance of membrane distillation is negatively affected by wetting and temperature polarization phenomena. In order to overcome these issues, advanced membranes have been developed in recent years. This review, which focuses specifically on membrane distillation presents the basic concepts associated with the mass and heat transfer through hydrophobic membranes, membrane properties, and advances in membrane materials. Photothermal materials for solar-driven membrane distillation applications are also presented and discussed.
Physical Review B, 2018
Silicene, the two-dimensional allotrope of silicon, is predicted to exist in a low-buckled honeyc... more Silicene, the two-dimensional allotrope of silicon, is predicted to exist in a low-buckled honeycomb lattice, characterized by semimetallic electronic bands with graphenelike energy-momentum dispersions around the Fermi level (represented by touching Dirac cones). Single layers of silicene are mostly synthesized by depositing silicon on top of silver, where, however, the different phases observed to date are so strongly hybridized with the substrate that not only the Dirac cones, but also the whole valence and conduction states of ideal silicene appear to be lost. Here, we provide evidence that at least part of this semimetallic behavior is preserved by the coexistence of more silicene phases, epitaxially grown on Ag(111). In particular, we combine electron energy loss spectroscopy and time-dependent density functional theory to characterize the low-energy plasmon of a multiphase-silicene/Ag(111) sample, prepared at controlled silicon coverage and growth temperature. We find that this mode survives the interaction with the substrate, being perfectly matched with the π-like plasmon of ideal silicene. We therefore suggest that the weakened interaction of multiphase silicene with the substrate may provide a unique platform with the potential to develop novel applications based on two-dimensional silicon systems.
Nanomaterials, 2020
Porous carbon materials are currently subjected to strong research efforts mainly due to their ex... more Porous carbon materials are currently subjected to strong research efforts mainly due to their excellent performances in energy storage devices. A sustainable process to obtain them is hydrothermal carbonization (HTC), in which the decomposition of biomass precursors generates solid products called hydrochars, together with liquid and gaseous products. Hydrochars have a high C content and are rich with oxygen-containing functional groups, which is important for subsequent activation. Orange pomace and orange peels are considered wastes and then have been investigated as possible feedstocks for hydrochars production. On the contrary, orange juice was treated by HTC only to obtain carbon quantum dots. In the present study, pure orange juice was hydrothermally carbonized and the resulting hydrochar was filtered and washed, and graphitized/activated by KOH in nitrogen atmosphere at 800 °C. The resulting material was studied by transmission and scanning electron microscopy, Raman spectro...
Applied Surface Science, 2021
Abstract The electronic properties of graphite with rotational stacking faults are strongly modif... more Abstract The electronic properties of graphite with rotational stacking faults are strongly modified with respect to Bernal-stacked graphite, with the recovery of the Dirac cones for sufficiently high misorientation angles. A particular case is represented by twisted bilayer graphene (TBLG), in which twist angles are univocally related to the frequency of rotation modes observed in Raman spectra. The electronic properties determined by Dirac fermions make highly desirable to develop simple routes to synthesize highly decoupled turbostratic graphite and TBLG, as an alternative to single-layer graphene (SLG) for graphene-based electronic devices. In this work, we present a synthesis of hollow iron microspheres wrapped by graphitic layers in water-submerged arc discharge experiments between graphite electrodes, with an iron wire inserted into the anode. The microspheres were studied by scanning electron microscopy, microprobe energy-dispersive X-ray spectroscopy and Raman spectroscopy. We observed domains showing rotation and combination Raman modes typical of TBLG with different rotation angles, together with domains made of turbostratic graphite. The twist angles found in TBLG domains are indicative of values of the Fermi velocity close to the value of SLG. Our results open a new road for the synthesis of robust graphitic materials with the electronic properties of SLG.
Physical Review B, 2019
We explore the broadband excitation spectrum of bulk PtTe2 using electron energy loss spectroscop... more We explore the broadband excitation spectrum of bulk PtTe2 using electron energy loss spectroscopy and density functional theory. In addition to infrared modes related to intraband 3D Dirac plasmon and interband transitions between the 3D Dirac bands, we observe modes at 3.9, 7.5 and 19.0 eV in the ultraviolet region. The comparison of the excitation spectrum with the calculated orbital-resolved density of states allows us to ascribe spectral features to transitions between specific electronic states. Additionally, we study the thickness dependence of the high-energy plasmon in the PtTe2 thin films. We show that, unlike graphene, the high-energy plasmon in PtTe2 thin film gets red-shifted by ∼2.5 eV with increasing thickness.
Nanomaterials
Reduced graphene oxide (rGO) is one of the most well-known graphene derivatives, which, due to it... more Reduced graphene oxide (rGO) is one of the most well-known graphene derivatives, which, due to its outstanding physical and chemical properties as well as its oxygen content, has been used for wastewater treatment technologies. Particularly, extra functionalized rGO is widely preferred for treating wastewater containing dyes or heavy metals. Nevertheless, the use of non-extra functionalized (pristine) rGO for the removal of cationic pollutants is not explored in detail or is ambiguous. Herein, pristine rGO—prepared by an eco-friendly protocol—is used for the removal of cationic pollutants from water, i.e., methylene blue (MB) and mercury-(II) (Hg-(II)). This work includes the eco-friendly synthesis process and related spectroscopical and morphological characterization. Most importantly, the investigated rGO shows an adsorption capacity of 121.95 mg g−1 for MB and 109.49 mg g−1 for Hg (II) at 298 K. A record adsorption time of 30 min was found for MB and 20 min for Hg (II) with an ef...
Carlo Rizza, ∗ Debasis Dutta, Barun Ghosh, 3 Francesca Alessandro, Chia-Nung Kuo, Chin Shan Lue, ... more Carlo Rizza, ∗ Debasis Dutta, Barun Ghosh, 3 Francesca Alessandro, Chia-Nung Kuo, Chin Shan Lue, Lorenzo S. Caputi, Arun Bansil, Amit Agarwal, Antonio Politano, 6, † and Anna Cupolillo Department of Physical and Chemical Sciences, University of L’Aquila, Via Vetoio 1, I-67100 L’Aquila, Italy Department of Physics, Indian Institute of Technology Kanpur, Kanpur-208016, India Department of Physics, Northeastern University, Boston, Massachusetts 02115, United States of America Department of Physics, University of Calabria, Via ponte Bucci, I-83036, Rende, Italy Department of Physics, National Cheng Kung University, 1 Ta-Hsueh Road 70101 Tainan, Taiwan CNR-IMM Istituto per la Microelettronica e Microsistemi, VIII strada 5, I-95121 Catania, Italy
Carbon nano-onions (CNOs), which consist of concentric graphitic shells, currently attract much a... more Carbon nano-onions (CNOs), which consist of concentric graphitic shells, currently attract much attention because of their unique structural and physical properties, which are different from the properties of the other carbon nanomaterials such as fullerenes, graphene, and carbon nanotubes (CNTs). Due to their small size, the large external surface area and high conductivity, CNOs are used for supercapacitor applications. The arc discharge underwater is an effective and simple method for the synthesis of larger CNOs in reasonable quantities. In this research, we have been obtained carbon nanomaterials using arc discharge in water between two high purity graphite electrodes. The main experimental techniques used to characterize carbon nanostructures have been Transmission Electron Microscopy (TEM) and Raman Spectroscopy. Among them, Raman spectroscopy is the most useful non-destructive technique capable of differentiating between these various structures. Our TEM images showed that t...