Davide Cozzoli - Academia.edu (original) (raw)

Papers by Davide Cozzoli

Science of Advanced Materials, Nov 1, 2015

We have developed a novel and straightforward approach for the green synthesis of reduced graphit... more We have developed a novel and straightforward approach for the green synthesis of reduced graphite oxide (rGO). First, graphite oxide (GO) was prepared by the Hummers' oxidation method, starting from high-surfacearea graphite. Then, rGO was generated from GO in aqueous suspension through a UV-irradiation treatment. The influence of different process parameters (including type of UV source, irradiation time and atmosphere) on the GO reduction efficiency was explored and evaluated on the basis of the data acquired by several experimental techniques, such as infrared spectroscopy in attenuated total reflectance mode, X-ray diffraction, UV-vis absorption spectrophotometry, X-ray photoelectron spectroscopy and thermogravimetry. The acquired results allowed identifying appropriate sets of reaction conditions under which GO reduction yield could be maximized. In particular, the highest reduction degree was obtained by exposing GO to UV light in a UV oven for 48 h under inert atmosphere. The reduction strategy developed by us represents an innovative low-cost and easy route to graphene-based nanomaterials, which does not require any stabilizer, photocatalyst or reducing agent. For this reason, our method represents an attractive environmentally friendly alternative approach for the preparation of stable rGO dispersions in large-scale amounts, to be utilizable in disparate engineering applications

Wiley-VCH Verlag GmbH & Co. KGaA eBooks, Jun 23, 2017

Nano Energy, Nov 1, 2017

Abstract The engineering of electrochemically active films based on structurally and geometricall... more Abstract The engineering of electrochemically active films based on structurally and geometrically controlled transition-metal oxide nanocrystals holds promise for the development of a new generation of energy-efficient dynamic windows that may enable a spectrally selective control of sunlight transmission over the near-infrared regime. Herein, the different spectro-electrochemical signatures of two sets of engineered nanotextured electrodes made of distinct anisotropic-shaped tungsten oxide building blocks are comparatively investigated. The electrodes were fabricated starting from corresponding one-dimensional colloidal nanocrystals, namely solid and longitudinally carved nanorods, respectively, which featured identical crystal phase and lattice orientation, but exposed two distinct space-filled volume structures with subtly different lattice parameters and nonequivalent types of accessible surfaces. The shape of nanocrystalline building blocks greatly impacted on the fundamental electrochemical charge-storage mechanisms and, hence on the electrochromic response of these electrodes, due to concomitant bulk and surface-structure effects that could not be entirely traced to mere differences in surface-to-volume ratio. Electrodes made of carved nanorods accommodated more than 80% of the total charge through surface-capacitance mechanisms. This unique prerogative was ultimately demonstrated to enable an outstanding spectral selectivity as well as an extremely efficient dynamic modulation of the optical transmittance at near-infrared frequencies (~ 80% in the range 700–1600 nm).

Acta Crystallographica Section A, Aug 29, 2010

Electron Crystallography of 2D protein crystals is a powerful tool for the determination of membr... more Electron Crystallography of 2D protein crystals is a powerful tool for the determination of membrane protein structure. It is, however, dependent on the quality of the 2D crystalline arrangement, and in the past suffered from the tilt-limited data collection scheme in form of a missing cone in Fourier space, producing resolution loss in the direction perpendicular to the membrane plane. We here describe a single-particle approach to 2D crystals, employing a maximum likelihood algorithm [1]. We further describe a solution for the full recovery of the missing cone data, based on projective constraint optimization that, that for sufficiently oversampled data produces complete recovery of unmeasured data in the missing cone. We apply this method to an experimental dataset of bacteriorhodopsin and show that, in addition to producing superior results compared to traditional reconstruction methods, full, reproducible, recovery of the missing cone from noisy data is possible. Finally, we present an automatic implementation of the refinement routine as open source, freely distributed, software to be included in our 2dx software package [2] (available at http://2dx.org).

Journal of Materials Chemistry C, 2021

Engineering physicochemical properties of two-dimensional transition metal dichalcogenide (2D-TMD... more Engineering physicochemical properties of two-dimensional transition metal dichalcogenide (2D-TMD) materials by surface manipulation is essential to enabling their practical and large-scale application. This is especially challenging for colloidal 2D-TMDs that are plagued by the unintentional formation of structural defects during the synthetic procedure. However, the available methods to manage surface states of 2D-TMDs in solution phase are still limited, hampering the production of high-quality colloidal 2D-TMD inks. Here, we demonstrate an efficient solution-phase strategy to passivate surface defect states of colloidal WS 2 nanoflakes with halide ligands, which results in the activation of their photoluminescence emission. Photophysical investigation and density functional theory calculations suggest that halide atoms enable the suppression of non-radiative recombination through the elimination of deep gap trap states and the introduction of localized states in the energy band structure from which excitons can efficiently recombine. Importantly, halide passivated WS 2 nanoflakes retain colloidal stability and photoluminescence emission after several weeks of storage in ambient atmosphere, corroborating the potential of developed WS 2 inks thereof.

Processes

Thin films of titanium dioxide (TiO2) nanocrystals, widely acknowledged for their unique physical... more Thin films of titanium dioxide (TiO2) nanocrystals, widely acknowledged for their unique physical-chemical properties and functionalities, are used in disparate technological fields, including photovoltaics, sensing, environmental remediation and energy storage. In this paper, the preparation of thin films consisting of anatase-phase TiO2 nanorods deposited using the matrix-assisted pulsed laser evaporation (MAPLE) technique and their characterization in terms of morphology, elemental composition and wettability are presented and discussed. Particular attention is paid to the effects of the laser fluence, varied over a broad range (F = 25, 50, 100 mJ/cm2), and to the role of the capping surfactants bound to the surface of the nanorod precursors. Whereas increasing fluence favored a partial removal of the surface-bound surfactants, a post-growth UV-light-driven photocatalytic treatment of the films was found to be necessary to reduce the incorporated fraction of organics to a further...

Nanoscale Advances, 2019

Non-hydrolytic synthesis assisted by long-chain amphiphilic surfactant is exploited to generate d... more Non-hydrolytic synthesis assisted by long-chain amphiphilic surfactant is exploited to generate dimension-controllable 2D-WS2 nanoflakes in a single-step protocol, where the chemical nature and steric hindrance of the alkylamine are the key points to modulate the lateral size finally achieved.

Advanced Sustainable Systems, 2017

Novel nanostructured films employing hyperbranched and all‐linear TiO2 nanorods have been develop... more Novel nanostructured films employing hyperbranched and all‐linear TiO2 nanorods have been developed with the aim to overcome the impediments to the diffusion of bulky redox shuttles in photo‐electrochemical devices. The porosity of the working electrodes has been tailored by appropriately selecting the nanocrystal building blocks to study how the electrode features affect the electrochemical parameters underlying the charge‐transport phenomena and the photovoltaic properties of dye‐sensitized solar cells. An optimized combination of porosity, light‐harvesting capability, and enhanced electron‐transport properties leads to a remarkable improvement of the device efficiency from 1.3% to 8.6%. These results suggest that it is indeed possible to properly design photoanodes based on shape‐engineered nanocrystals, which can be suitable for different electrochemical devices such as fuel cells or storage devices employing viscous or quasi‐solid electrolytes.

Physical chemistry chemical physics : PCCP, Jan 25, 2018

Thanks to their high stability, good optoelectronic and extraordinary electrochromic properties, ... more Thanks to their high stability, good optoelectronic and extraordinary electrochromic properties, tungsten oxides are among the most valuable yet underexploited materials for energy conversion applications. Herein, colloidal one-dimensional carved nanocrystals of reduced tungsten trioxide (WO3-x) are successfully integrated, for the first time, as a hole-transporting layer (HTL) into CH3NH3PbI3 perovskite solar cells with a planar inverted device architecture. Importantly, the use of such preformed nanocrystals guarantees the facile solution-cast-only deposition of a homogeneous WO3-x thin film at room temperature, allowing achievement of the highest power conversion efficiency ever reported for perovskite solar cells incorporating raw and un-doped tungsten oxide based HTL.

Science of Advanced Materials, 2015

Sensors and Actuators B: Chemical, 2012

ABSTRACT Brookite titanium dioxide (TiO2) nanorods, synthesized by a surfactant-assisted aminolys... more ABSTRACT Brookite titanium dioxide (TiO2) nanorods, synthesized by a surfactant-assisted aminolysis route, were used as precursors for the fabrication of thin films by using the matrix-assisted pulsed-laser deposition (MAPLE) technique. Thin films with controllable thickness were grown on a variety of substrates for different characterizations. High-resolution scanning and transmission electron microscopy investigations evidenced the formation of rough TiO2 films incorporating individually distinguishable nanocrystals with different shapes. Suitable alumina substrates equipped with interdigitated electrical contacts (IDC) and heating elements were used to fabricate gas-sensing devices based on resistive transduction mechanism. Electrical characterization measurements in controlled environment were carried out. Typical gas sensor parameters (such as gas response, sensitivity, stability and detection limit) towards selected oxidizing and reducing gases, namely NO2 and CO, respectively, were extracted in dark condition. Very interesting optically activated enhancement of the response towards NO2 oxidizing gas was achieved in controlled atmosphere upon irradiating the sensing layer with UV light with low energy close to the TiO2 sensing layer band-gap width.

Sensors and Actuators B: Chemical, 2007

This work explores the potential of thin films composed of shape-controlled colloidal TiO2 nanocr... more This work explores the potential of thin films composed of shape-controlled colloidal TiO2 nanocrystals in optical gas sensing applications. To this purpose, an optical characterization of nanocrystal thin films has been performed by means of UV–vis spectroscopy and surface plasmon resonance (SPR) technique. In particular, this technique has been used as optical transduction method to test the sensing properties of

Optics Communications, 2013

Journal of Applied Physics, 2012

The sensing performance comparisons presented in this work were carried out by exploiting a suita... more The sensing performance comparisons presented in this work were carried out by exploiting a suitable magneto-plasmonic sensor in both the traditional surface plasmon resonance configuration and the innovative magneto-optic surface plasmon resonance one. The particular multilayer transducer was functionalized with TiO2 Brookite nanorods layers deposited by matrix assisted pulsed laser evaporation, and its sensing capabilities were monitored in a controlled atmosphere towards different concentrations of volatile organic compounds mixed in dry air.

ChemPhysChem, 2016

We have developed a general X‐ray powder diffraction (XPD) methodology for the simultaneous struc... more We have developed a general X‐ray powder diffraction (XPD) methodology for the simultaneous structural and compositional characterization of inorganic nanomaterials. The approach is validated on colloidal tungsten oxide nanocrystals (WO3−x NCs), as a model polymorphic nanoscale material system. Rod‐shaped WO3‐x NCs with different crystal structure and stoichiometry are comparatively investigated under an inert atmosphere and after prolonged air exposure. An initial structural model for the as‐synthesized NCs is preliminarily identified by means of Rietveld analysis against several reference crystal phases, followed by atomic pair distribution function (PDF) refinement of the best‐matching candidates (static analysis). Subtle stoichiometry deviations from the corresponding bulk standards are revealed. NCs exposed to air at room temperature are monitored by XPD measurements at scheduled time intervals. The static PDF analysis is complemented with an investigation into the evolution of...

Science of Advanced Materials, Nov 1, 2015

We have developed a novel and straightforward approach for the green synthesis of reduced graphit... more We have developed a novel and straightforward approach for the green synthesis of reduced graphite oxide (rGO). First, graphite oxide (GO) was prepared by the Hummers' oxidation method, starting from high-surfacearea graphite. Then, rGO was generated from GO in aqueous suspension through a UV-irradiation treatment. The influence of different process parameters (including type of UV source, irradiation time and atmosphere) on the GO reduction efficiency was explored and evaluated on the basis of the data acquired by several experimental techniques, such as infrared spectroscopy in attenuated total reflectance mode, X-ray diffraction, UV-vis absorption spectrophotometry, X-ray photoelectron spectroscopy and thermogravimetry. The acquired results allowed identifying appropriate sets of reaction conditions under which GO reduction yield could be maximized. In particular, the highest reduction degree was obtained by exposing GO to UV light in a UV oven for 48 h under inert atmosphere. The reduction strategy developed by us represents an innovative low-cost and easy route to graphene-based nanomaterials, which does not require any stabilizer, photocatalyst or reducing agent. For this reason, our method represents an attractive environmentally friendly alternative approach for the preparation of stable rGO dispersions in large-scale amounts, to be utilizable in disparate engineering applications

Wiley-VCH Verlag GmbH & Co. KGaA eBooks, Jun 23, 2017

Nano Energy, Nov 1, 2017

Abstract The engineering of electrochemically active films based on structurally and geometricall... more Abstract The engineering of electrochemically active films based on structurally and geometrically controlled transition-metal oxide nanocrystals holds promise for the development of a new generation of energy-efficient dynamic windows that may enable a spectrally selective control of sunlight transmission over the near-infrared regime. Herein, the different spectro-electrochemical signatures of two sets of engineered nanotextured electrodes made of distinct anisotropic-shaped tungsten oxide building blocks are comparatively investigated. The electrodes were fabricated starting from corresponding one-dimensional colloidal nanocrystals, namely solid and longitudinally carved nanorods, respectively, which featured identical crystal phase and lattice orientation, but exposed two distinct space-filled volume structures with subtly different lattice parameters and nonequivalent types of accessible surfaces. The shape of nanocrystalline building blocks greatly impacted on the fundamental electrochemical charge-storage mechanisms and, hence on the electrochromic response of these electrodes, due to concomitant bulk and surface-structure effects that could not be entirely traced to mere differences in surface-to-volume ratio. Electrodes made of carved nanorods accommodated more than 80% of the total charge through surface-capacitance mechanisms. This unique prerogative was ultimately demonstrated to enable an outstanding spectral selectivity as well as an extremely efficient dynamic modulation of the optical transmittance at near-infrared frequencies (~ 80% in the range 700–1600 nm).

Acta Crystallographica Section A, Aug 29, 2010

Electron Crystallography of 2D protein crystals is a powerful tool for the determination of membr... more Electron Crystallography of 2D protein crystals is a powerful tool for the determination of membrane protein structure. It is, however, dependent on the quality of the 2D crystalline arrangement, and in the past suffered from the tilt-limited data collection scheme in form of a missing cone in Fourier space, producing resolution loss in the direction perpendicular to the membrane plane. We here describe a single-particle approach to 2D crystals, employing a maximum likelihood algorithm [1]. We further describe a solution for the full recovery of the missing cone data, based on projective constraint optimization that, that for sufficiently oversampled data produces complete recovery of unmeasured data in the missing cone. We apply this method to an experimental dataset of bacteriorhodopsin and show that, in addition to producing superior results compared to traditional reconstruction methods, full, reproducible, recovery of the missing cone from noisy data is possible. Finally, we present an automatic implementation of the refinement routine as open source, freely distributed, software to be included in our 2dx software package [2] (available at http://2dx.org).

Journal of Materials Chemistry C, 2021

Engineering physicochemical properties of two-dimensional transition metal dichalcogenide (2D-TMD... more Engineering physicochemical properties of two-dimensional transition metal dichalcogenide (2D-TMD) materials by surface manipulation is essential to enabling their practical and large-scale application. This is especially challenging for colloidal 2D-TMDs that are plagued by the unintentional formation of structural defects during the synthetic procedure. However, the available methods to manage surface states of 2D-TMDs in solution phase are still limited, hampering the production of high-quality colloidal 2D-TMD inks. Here, we demonstrate an efficient solution-phase strategy to passivate surface defect states of colloidal WS 2 nanoflakes with halide ligands, which results in the activation of their photoluminescence emission. Photophysical investigation and density functional theory calculations suggest that halide atoms enable the suppression of non-radiative recombination through the elimination of deep gap trap states and the introduction of localized states in the energy band structure from which excitons can efficiently recombine. Importantly, halide passivated WS 2 nanoflakes retain colloidal stability and photoluminescence emission after several weeks of storage in ambient atmosphere, corroborating the potential of developed WS 2 inks thereof.

Processes

Thin films of titanium dioxide (TiO2) nanocrystals, widely acknowledged for their unique physical... more Thin films of titanium dioxide (TiO2) nanocrystals, widely acknowledged for their unique physical-chemical properties and functionalities, are used in disparate technological fields, including photovoltaics, sensing, environmental remediation and energy storage. In this paper, the preparation of thin films consisting of anatase-phase TiO2 nanorods deposited using the matrix-assisted pulsed laser evaporation (MAPLE) technique and their characterization in terms of morphology, elemental composition and wettability are presented and discussed. Particular attention is paid to the effects of the laser fluence, varied over a broad range (F = 25, 50, 100 mJ/cm2), and to the role of the capping surfactants bound to the surface of the nanorod precursors. Whereas increasing fluence favored a partial removal of the surface-bound surfactants, a post-growth UV-light-driven photocatalytic treatment of the films was found to be necessary to reduce the incorporated fraction of organics to a further...

Nanoscale Advances, 2019

Non-hydrolytic synthesis assisted by long-chain amphiphilic surfactant is exploited to generate d... more Non-hydrolytic synthesis assisted by long-chain amphiphilic surfactant is exploited to generate dimension-controllable 2D-WS2 nanoflakes in a single-step protocol, where the chemical nature and steric hindrance of the alkylamine are the key points to modulate the lateral size finally achieved.

Advanced Sustainable Systems, 2017

Novel nanostructured films employing hyperbranched and all‐linear TiO2 nanorods have been develop... more Novel nanostructured films employing hyperbranched and all‐linear TiO2 nanorods have been developed with the aim to overcome the impediments to the diffusion of bulky redox shuttles in photo‐electrochemical devices. The porosity of the working electrodes has been tailored by appropriately selecting the nanocrystal building blocks to study how the electrode features affect the electrochemical parameters underlying the charge‐transport phenomena and the photovoltaic properties of dye‐sensitized solar cells. An optimized combination of porosity, light‐harvesting capability, and enhanced electron‐transport properties leads to a remarkable improvement of the device efficiency from 1.3% to 8.6%. These results suggest that it is indeed possible to properly design photoanodes based on shape‐engineered nanocrystals, which can be suitable for different electrochemical devices such as fuel cells or storage devices employing viscous or quasi‐solid electrolytes.

Physical chemistry chemical physics : PCCP, Jan 25, 2018

Thanks to their high stability, good optoelectronic and extraordinary electrochromic properties, ... more Thanks to their high stability, good optoelectronic and extraordinary electrochromic properties, tungsten oxides are among the most valuable yet underexploited materials for energy conversion applications. Herein, colloidal one-dimensional carved nanocrystals of reduced tungsten trioxide (WO3-x) are successfully integrated, for the first time, as a hole-transporting layer (HTL) into CH3NH3PbI3 perovskite solar cells with a planar inverted device architecture. Importantly, the use of such preformed nanocrystals guarantees the facile solution-cast-only deposition of a homogeneous WO3-x thin film at room temperature, allowing achievement of the highest power conversion efficiency ever reported for perovskite solar cells incorporating raw and un-doped tungsten oxide based HTL.

Science of Advanced Materials, 2015

Sensors and Actuators B: Chemical, 2012

ABSTRACT Brookite titanium dioxide (TiO2) nanorods, synthesized by a surfactant-assisted aminolys... more ABSTRACT Brookite titanium dioxide (TiO2) nanorods, synthesized by a surfactant-assisted aminolysis route, were used as precursors for the fabrication of thin films by using the matrix-assisted pulsed-laser deposition (MAPLE) technique. Thin films with controllable thickness were grown on a variety of substrates for different characterizations. High-resolution scanning and transmission electron microscopy investigations evidenced the formation of rough TiO2 films incorporating individually distinguishable nanocrystals with different shapes. Suitable alumina substrates equipped with interdigitated electrical contacts (IDC) and heating elements were used to fabricate gas-sensing devices based on resistive transduction mechanism. Electrical characterization measurements in controlled environment were carried out. Typical gas sensor parameters (such as gas response, sensitivity, stability and detection limit) towards selected oxidizing and reducing gases, namely NO2 and CO, respectively, were extracted in dark condition. Very interesting optically activated enhancement of the response towards NO2 oxidizing gas was achieved in controlled atmosphere upon irradiating the sensing layer with UV light with low energy close to the TiO2 sensing layer band-gap width.

Sensors and Actuators B: Chemical, 2007

This work explores the potential of thin films composed of shape-controlled colloidal TiO2 nanocr... more This work explores the potential of thin films composed of shape-controlled colloidal TiO2 nanocrystals in optical gas sensing applications. To this purpose, an optical characterization of nanocrystal thin films has been performed by means of UV–vis spectroscopy and surface plasmon resonance (SPR) technique. In particular, this technique has been used as optical transduction method to test the sensing properties of

Optics Communications, 2013

Journal of Applied Physics, 2012

The sensing performance comparisons presented in this work were carried out by exploiting a suita... more The sensing performance comparisons presented in this work were carried out by exploiting a suitable magneto-plasmonic sensor in both the traditional surface plasmon resonance configuration and the innovative magneto-optic surface plasmon resonance one. The particular multilayer transducer was functionalized with TiO2 Brookite nanorods layers deposited by matrix assisted pulsed laser evaporation, and its sensing capabilities were monitored in a controlled atmosphere towards different concentrations of volatile organic compounds mixed in dry air.

ChemPhysChem, 2016

We have developed a general X‐ray powder diffraction (XPD) methodology for the simultaneous struc... more We have developed a general X‐ray powder diffraction (XPD) methodology for the simultaneous structural and compositional characterization of inorganic nanomaterials. The approach is validated on colloidal tungsten oxide nanocrystals (WO3−x NCs), as a model polymorphic nanoscale material system. Rod‐shaped WO3‐x NCs with different crystal structure and stoichiometry are comparatively investigated under an inert atmosphere and after prolonged air exposure. An initial structural model for the as‐synthesized NCs is preliminarily identified by means of Rietveld analysis against several reference crystal phases, followed by atomic pair distribution function (PDF) refinement of the best‐matching candidates (static analysis). Subtle stoichiometry deviations from the corresponding bulk standards are revealed. NCs exposed to air at room temperature are monitored by XPD measurements at scheduled time intervals. The static PDF analysis is complemented with an investigation into the evolution of...