Nicola Sangiorgi - Academia.edu (original) (raw)

Papers by Nicola Sangiorgi

Proceedings of the Materials for Sustainable Development Conference (MAT-SUS)

ISEECap 2019, 2019

In this work the development of flexible graphite electrodes suitably modified for their use in t... more In this work the development of flexible graphite electrodes suitably modified for their use in the preparation of pseudocapacitors is investigated. The optimal conditions for the electrosynthesis of nanocomposite films consisting of polyanaline (PANI, a conductive polymer)[1] and nanoparticles based on bare and/or functionalized magnetite and gold are studied. In particular, magnetite and Au/magnetite nanoparticles labelled as Au/Fe3O4 and Au/Fe3O4@Yne (Yne = propynylcarbamate)[2,3,4], are used to obtain modified PANI electrodes with improved performance in respect of pristine PANI in terms of charge density, surface area and storage capacity. The electrosynthesis of the polymer and polymer-composites is carried out through cyclic voltammetry, in aqueous solution. The electrodes are characterized by CV, SEM, charge-discharge test (C/D) and impedance test (EIS). Finally, the best performing electrodes are used to assemble a symmetrical supercapacitor

Organometallic systems to sustain a better future, 2013

Sustainable Energy & Fuels

In a Photo-Electrochemical (PEC) cell rapid spatial separation of the photo-generated carriers an... more In a Photo-Electrochemical (PEC) cell rapid spatial separation of the photo-generated carriers and their transport kinetics within the photo-electrodes materials are fundamental to achieving high-performance devices and avoiding charge recombination....

Biomaterials Science, 2022

This work describes the development of electroconductive hydrogels as injectable matrices for neu... more This work describes the development of electroconductive hydrogels as injectable matrices for neural tissue regeneration by exploiting a biocompatible conductive polymer – i.e. poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) – combined with a biomimetic...

J. Mater. Chem. B, 2017

Bioinspired mineralization of a CaP wide-band gap semiconductor on conductive natural fibers.

Applied Clay Science, 2017

This paper describes the electrosynthesis and characterization in alkaline solutions of two layer... more This paper describes the electrosynthesis and characterization in alkaline solutions of two layered double hydroxides (LDHs) containing Co as divalent cation and Al or Fe as trivalent one on Pt supports. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) experiments demonstrated a capacitive behaviour. LDHs containing Al 3+ or Fe 3+ displayed different responses, highlighting a key role of the trivalent metal. High specific capacitances calculated from charge-discharge experiments at a current density of 1 A g − 1 , were displayed by the two materials and resulted 854 and 869 F g − 1 for the Al or Fe containing LDH, respectively. The long-term cycling capability was also investigated giving satisfactory results. The presence of Fe improves the performance of the LDH as pseudocapacitor, especially to achieve better performances in terms of energy and power densities. In view of the development of low cost supercapacitors preliminary tests aimed to deposit Co based LDHs on a large area graphite substrate were also successfully carried out.

European Journal of Organic Chemistry, 2017

A synthetic sequence for the preparation of fully conjugated, 2,7-disubstituted fluorazone (9H-py... more A synthetic sequence for the preparation of fully conjugated, 2,7-disubstituted fluorazone (9H-pyrrolo[1,2-a]indol-9-one) derivatives was developed, comprising Elming-Clauson-Kaas type pyrrole formation, POCl3-mediated ring closure, selective halogenation and elongation of the conjugate backbone via cross-coupling reactions. As a proof of principle, such methodology was used to prepare for the first time two organic D-π-A dyes containing the fluorazone moiety. The new compounds displayed broad absorption of visible light when adsorbed on nanocrystalline TiO2 and electrochemical properties compatible with their employment as photosensitizers in dye-sensitized solar cells. Small-scale photovoltaic devices fabricated with the fluorazone dyes yielded power conversion efficiencies in the 2.1-2.4% range, corresponding to approx. 70% of the efficiency obtained with reference organic dye DF15 under the same conditions.

Optical Materials, 2017

The optical band gap energy and the electronic processes involved are important parameters of a s... more The optical band gap energy and the electronic processes involved are important parameters of a semiconductor material and it is therefore important to determine their correct values. Among the possible methods, the spectrophotometric is one of the most common. Several methods can be applied to determine the optical band gap energy and still now a defined consensus on the most suitable one has not been established. A highly diffused and accurate optical method is based on Tauc relationship, however to apply this equation is necessary to know the nature of the electronic transitions involved commonly related to the coefficient n. For this purpose, a spectrophotometric technique was used and we developed a graphical method for electronic transitions and band gap energy determination for samples in powder form. In particular, the n coefficient of Tauc equation was determined thorough mathematical elaboration of experimental results on TiO 2 (anatase), ZnO, and SnO 2. The results were used to calculate the band gap energy values and then compared with the information obtained by Ultraviolet Photoelectron Spectroscopy (UPS). This approach provides a quick and accurate method for band gap determination through n coefficient calculation. Moreover, this simple but reliable method can be used to evaluate the nature of electronic transition that occurs in a semiconductor material in powder form.

Journal of Photochemistry and Photobiology A: Chemistry, 2016

Quasi-solid dye-sensitized solar cells were obtained by coupling N719 dye with a cobalt gel elect... more Quasi-solid dye-sensitized solar cells were obtained by coupling N719 dye with a cobalt gel electrolyte. Firstly, the compatibility of the liquid [Co(bpy) 3 ] 3+/2+ redox mediator with N719 was improved by modifying the surface of sensitized photoanode, which resulted in an increase in efficiency of over 100%. Most importantly, a novel room-temperature route for producing a [Co(bpy) 3 ] 3+/2+-PMMA gel electrolyte was introduced for the first time. The formation of the gel phase was demonstrated by rheological analyses and the electrolyte was subjected to an extensive electrochemical characterization. The derived quasi-solid devices attained 70% of the efficiency of the liquid ones, and showed a degradation of only 15% after 120 days, which proved the high stability of the developed system. 2016 Elsevier B.V. All rights reserved.

Chemical Engineering Journal, 2014

Abstract Synthetic hydroxy-apatite was tested as a potential new material for CO2 capture at high... more Abstract Synthetic hydroxy-apatite was tested as a potential new material for CO2 capture at high temperature, over the operation limit of CaO-based sorbents. Some porous granules of hydroxy-apatite were prepared ad hoc. They were shown to absorb CO2 upon dehydroxylation in the very high temperature range of 900–1200 °C, resulting in A-type carbonated apatite. No appreciable decay of the absorbing capacity was observed with a higher number of absorbing–desorbing cycles, differently from what happens in a conventional chemical sorbent, e.g. calcined natural calcium carbonate. The CO2 carrying capacity was maximum at 1000–1100 °C and very close to the theoretical limit of 2.6% by mass. The macro-granule porosity network appeared to be effective in making the sites available for CO2 capture. At first glance, the process appeared to be chemically controlled. The pre-treatment temperature of the porous granules also had an impact on the sorption capacity. As a first proof of concept, the results obtained by thermogravimetric analysis, and supported by FTIR and XRD analysis, were confirmed by tests carried out in a laboratory-scale reactor, operated as a fixed bed.

Journal of Electroanalytical Chemistry, Apr 1, 2022

Applied Clay Science, 2021

Layered Double Hydroxides (LDH) are versatile materials that can be applied to different fields. ... more Layered Double Hydroxides (LDH) are versatile materials that can be applied to different fields. Recently their employment in Dye-Sensitized Solar Cells (DSSCs) technology has been reported. The heart of this technology is the photoanode, a semiconductor layer sensitized with dye molecules able to absorb the sunlight. However, the traditional dye molecules are quite expensive and sensitive to thermal degradation and the sensitization process requires time and costs. The possibility to directly intercalate the dye in the LDH interlayer makes these materials very promising as innovative photoanodes. This aspect in fact would help to reduce both the time and the costs, overcome charge-transfer and recombination phenomena issues and finally increase the Photo-Conversion Efficiency (PCE) and stability. In this work, an Eosin Y-intercalated ZnAl LDH was prepared by coprecipitation and applied as photoanode material. For this purpose, a screen-printing ink was formulated and then applied o...

Energies

In this work, copper oxides-based photocathodes for photoelectrochemical cells (PEC) were produce... more In this work, copper oxides-based photocathodes for photoelectrochemical cells (PEC) were produced for the first time by screen printing. A total 7 × 10−3 g/m2 glycerine trioleate was found as optimum deflocculant amount to assure stable and homogeneous inks, based on CuO nano-powder. The inks were formulated considering different binder amounts and deposited producing films with homogenous thickness, microstructure, and roughness. The as-produced films were thermally treated to obtain Cu2O- and Cu2O/CuO-based electrodes. The increased porosity obtained by adding higher amounts of binder in the ink positively affected the electron transfer from the surface of the electrode to the electrolyte, thus increasing the corresponding photocurrent values. Moreover, the Cu2O/CuO system showed a higher charge carrier and photocurrent density than the Cu2O-based one. The mixed Cu2O/CuO films allowed the most significant hydrogen production, especially in slightly acid reaction conditions.

Solar Energy Materials and Solar Cells

Abstract Fiber-shaped Dye-Sensitized Solar Cells (DSSFs) represent one of the most interesting te... more Abstract Fiber-shaped Dye-Sensitized Solar Cells (DSSFs) represent one of the most interesting technologies aimed at the light harvesting and the production of electricity for wearable applications. In order to boost DSSFs commercialization, their production costs and environmental impact must be reduced. To this end, a suitable strategy could be to build thin film-based devices endowed with metal-free organic sensitizers, exploiting their higher molar extinction coefficients compared to typical ruthenium-containing organometallic dyes. In this work, three thiazolo[5,4-d]thiazole-based organic dyes, TTZ3, TTZ5 and TTZ7, capable of strongly absorb visible light, were used for the first time to manufacture titanium wire-based DSSFs. DSSFs based on a thin TiO2 layer (5 μm) sensitized with the three organic dyes were prepared and tested and the obtained results show that power conversion efficiencies for the organic dyes (0.80%) are higher than that obtained with the reference N719 dye (0.45%). An efficiency of 0.99% with short circuit current density equal to 3 mA/cm2 was achieved when the TTZ7-based DSSFs were tested in diffuse illumination condition, highlighting the supremacy of these dyes compared to the metal-organic reference. The excellent photovoltaic performances of TTZ dyes were attributed to their better light harvesting properties, resulting in the production of higher photocurrent densities, which was confirmed by the electrochemical impedance spectroscopy (EIS) analysis. The superiority of organic dyes on DSSFs performances compared to N719, shown for the first time in this work, support the real possibility to apply these molecules for the preparation of efficient light-harvesting devices based on thin film photoanodes.

Electrochimica Acta

Abstract In this work new energy storage components were prepared depositing films made of polyan... more Abstract In this work new energy storage components were prepared depositing films made of polyaniline (PANI) modified with gold/magnetite nanoparticles on flexible graphite foils. Three types of composite materials termed PANI/Fe3O4, PANI/Au/Fe3O4 and PANI/Au/Fe3O4@Yne (where @Yne is a propynylcarbamate group) were obtained by electrosynthesis. Galvanostatic charge-discharge (CD) and impedance tests (EIS) were performed to verify their efficiency in charge storage properties: for the gold-containing electrodes PANI/Au/Fe3O4 and PANI/Au/Fe3O4@Yne areal capacities values of 45.6 and 46.5 mAh cm−2 were found in 0.5 M H2SO4 + 0.1 M LiClO4 electrolyte solution at a current density of 0.5 mA cm−2. These values are twofold higher than those found for PANI/Fe3O4 electrodes and fourfold greater than those for PANI alone (11.0 mAh cm−2). In turn PANI/Au/Fe3O4 and PANI/Au/Fe3O4@Yne were employed to assemble gel-state symmetric devices. CD, EIS and longtime resistance tests were made on the new devices that displayed an areal capacities of 100.0 mAh cm−2 for PANI/Au/Fe3O4 and 73.6 mAh cm−2 PANI/Au/Fe3O4@Yne respectively. To our knowledge this is the first time that AuNP–modified magnetite nanoparticles are used in energy storage devices preparation.