Luigi Stagi

Luigi Stagi
Università degli Studi di Sassari | UNISS · Laboratory of Materials Science and Nanotechnology

PhD

About

52
Publications
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624
Citations

Publications

Publications (52)
Article
Halide perovskite colloidal nanocrystals have recently gained much attention thanks to their superior stability compared with their bulk counterpart and to their unique optical properties. In this paper, two systems combining nanocrystals and nanoporous gold are studied to create an optimal metal semiconductor heterojunction that can be used in pho...
Article
Thermal polymerization of glycine, the simplest amino acid bearing only one alfa carbon atom, is not an efficient process in mild conditions. Hydrothermal processing of glycine produces only small peptides, up to 4 units on average, with only a fraction of glycine that reacts. In the present work, we have used boric acid as a catalyst to promote th...
Article
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Heterostructures formed by anatase nanotitania and bidimensional semiconducting materials are expected to become the next-generation photocatalytic materials with an extended operating range and higher performances. The capability of fabricating optically transparent photocatalytic thin films is also a highly demanded technological issue, and incre...
Article
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Bioimaging supported by nanoparticles requires low cost, highly emissive and photostable systems with low cytotoxicity. Carbon dots (C-dots) offer a possible solution, even if controlling their properties is not always straightforward, not to mention their potentially simple synthesis and the fact that they do not exhibit long-term photostability i...
Article
The outbreak of the Covid-19 pandemic due to the SARS-CoV-2 coronavirus has accelerated the search for innovative antivirals with possibly broad-spectrum efficacy. One of the possible strategies is to inhibit the replication of the virus by preventing or limiting its entry into the cells. Nanomaterials derived from lysine, an essential amino acid c...
Article
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Graphene-enhanced Raman scattering (GERS) produces enhancement of the Raman signal, which is based on chemical rather than electromagnetic mechanism such as in the surface-enhanced Raman scattering. Graphene oxide, amino- and guanidine-functionalized graphene oxide, exfoliated graphene, and commercial graphene nanoplatelets have been used to invest...
Article
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A series of 6-aryl coumarin dyes were synthesized in satisfactory yields by Pd-catalyzed Suzuki cross-coupling reactions with a panel of boronic acids and coumarin bromides. Photophysical studies highlighted a large Stoke shift and interesting fluorescence quantum yield for these compounds. Optical properties were also investigated with the aid of...
Article
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The coronavirus pandemic (COVID-19) had spread rapidly since December 2019, when it was first identified in Wuhan, China. As of April 2021, more than 130 million cases have been confirmed, with more than 3 million deaths, making it one of the deadliest pandemics in history. Different approaches must be put in place to confront a new pandemic: commu...
Article
A novel blue excitable green fluorescent triazine-based material with high thermal stability (up to 350 °C) has been synthesized. Solid-state structural characterizations showed bright solid-state photoluminescence centered at 490 nm with an internal quantum yield (iQY) up to 40%. The coordination capabilities offered by the presence of a multi nit...
Article
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The polycondensation of amino acids can originate complex polymers that display fascinating structural and optical properties. Thermally induced amidation of l-lysine allows forming a branched polymer without the support of any catalyst. The polycondensation is completed at 240–250 °C; at higher temperatures, the amino acid degrades. The obtained p...
Article
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Nitrite ions pose a severe problem to human health justifying the need for fast and reliable detection of their presence in freshwater. Here we report a method to detect nitrite by photoluminescence of amino-rich carbon dots (C-dots). The dots are synthesized from p-phenylenediamine through a solvothermal treatment in ethanol. When nitrites ions ar...
Article
Hexagonal boron nitride (h-BN) nanodots of 10 nm have been synthesized via top-down route from bulk powders. A combination of ultrasonic and thermal treatments in phosphoric acid has been used to achieve edge etching and size reduction to the nanoscale. A new emission in the ultraviolet region, correlated to a characteristic infrared-active vibrati...
Article
CsPbI3 inorganic perovskite is synthesized by a solvent-free, solid-state reaction, and its structural and optical properties can be deeply investigated using a multi-technique approach. X-ray Diffraction (XRD) and Raman measurements, optical absorption, steady-time and time-resolved luminescence, as well as High-Resolution Transmission Electron Mi...
Article
Hexagonal boron nitride (h-BN) nanodots of 10 nm have been synthesized via top-down route from bulk powders. A combination of ultrasonic and thermal treatments in phosphoric acid has been used to achieve edge etching and size reduction to the nanoscale. A new emission in the ultraviolet region, correlated to a characteristic infrared-active vibrati...
Preprint
Full-text available
Totally inorganic perovskites are playing an increasingly important role for their potential applications in optoelectronics devices. However, a big problem to be solved is the role of the different phases, the presence of which is closely linked to the growth method and to the role of impurities. In this article, we propose a solvent-free, solid-s...
Article
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The fabrication of optically active heterostructures in the shape of mesostructured thin films is a highly challenging task. It requires an integrated process to allow in one-step incorporating the two-dimensional materials within the mesoporous ordered host without disrupting the pore organization. Hexagonal boron nitride (BN) nanosheets have been...
Article
Full-text available
The molecular emission model is the most accredited one to explain the emission properties of carbon dots (CDs) in a low-temperature bottom-up synthesis approach. In the case of citric acid and urea, the formation of a citrazinic acid (CZA) single monomer and oligomers is expected to affect the optical properties of the CDs. It is therefore mandato...
Article
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Functionalization of boron nitride (BN) materials with hydroxyls has attracted great attention to accomplish better performances at micro- and nanoscale. BN surface hydroxylation, in fact, induces a change in properties and allows expanding the fields of application. In this review, we have summarized the state-of-the-art in developing hydroxylated...
Article
The study of new phosphors requires in-depth knowledge of the mechanisms and radiative emission paths and, with this aim, the study here reported focuses on the emission properties of CaZnOS crystals single doped with Terbium and co-doped with Terbium and Europium. By studying the optical properties and, in particular, the kinetics of recombination...
Article
Carbonized polymer dots (CPDs), a peculiar type of Carbon dots, show extremely high quantum yields, making them very attractive nanostructures for application in optics and biophotonics. The origin of CPD strong photoluminescence resides in a complicated interplay of several radiative mechanisms. To understand the correlation between CPD processing...
Article
In recent years, carbon dots (CDs) have attracted considerable attention for their potential application in photonics and optoelectronics. One of the main limitations in realizing efficient and reliable solid-state devices is the aggregation-caused quenching effect. At a short distance, the mutual interaction among nanoparticles enhances the non-ra...
Article
Full-text available
The origin of carbon-dots (C-dots) fluorescence and its correlation with the dots structure still lack a comprehensive model. In particular, the core-shell model does not always fit with the experimental results, which, in some cases, suggest a molecular origin of the fluorescence. To gain a better insight, we have studied the response of molecular...
Article
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The appearance of new and lethal viruses and their potential threat urgently requires innovative antiviral systems. In addition to the most common and proven pharmacological methods, nanomaterials can represent alternative resources to fight viruses at different stages of infection, by a selective action or in a broad spectrum. A fundamental requir...
Article
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Citrazinic acid (CZA) is a weakly fluorescent molecular compound whose optical properties are dependent on aggregation states and chemical environment. This molecule and its derivatives have been recently identified as the source of the intense blue emission of carbon dots obtained from citric acid with a nitrogen source, such as ammonia or urea. C...
Article
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Highly fluorescent blue and green-emitting carbon dots have been designed to be integrated into sol-gel processing of hybrid organic-inorganic materials through surface modification with an organosilane, 3-(aminopropyl)triethoxysilane (APTES). The carbon dots have been synthesised using citric acid and urea as precursors; the intense fluorescence e...
Article
Understanding the luminescence of carbon dots is a highly challenging task because of the complex reactions involved in the synthesis process. Several by-products form at different reaction stages and become possible sources of emission. Citrazinic acid and its derivatives, in particular, have been identified as intermediates that give rise to blue...
Cover Page
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Despite the potential applications in several technological fields, 2D materials are at their early stages. Among them, boron nitride-based systems are still far from having been comprehensively studied. The possibilities of practical applications extend to very varied fields, from mechanics to optics. However, from careful observation of the exper...
Article
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The discovery of graphene has paved the way for intense research into 2D materials which is expected to have a tremendous impact on our knowledge of material properties in small dimensions. Among other materials, boron nitride (BN) nanomaterials have shown remarkable features with the possibility of being used in a large variety of devices. Photoni...
Article
The optical properties of microwave synthesized Carbon Dots dispersed in water and in mesoporous ordered silica are reported. The fluorescence characteristics of bare carbon dots are compared to the ones of nitrogen-doped samples, nitrogen doping being exploited to increase the emission efficiency. Two emission bands in the blue-green region, at ab...
Article
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In this work we analysed the optical and structural properties of Ce:YAG regenerated phosphors. The concentrate resulted as the final product of an industrial recycling process of waste electrical and electronic equipment (WEEE), and in particular fluorescent powders coming from spent lamps treatment plant. The waste pristine materials were re-util...
Article
The optical and electron properties of three different s-triazine derivatives are investigated to ascertain the role of the donor acceptor character in amine-triazine systems depending on the bridging radical of the ammine group. The three derivatives were obtained starting from three different ammine compounds allowing to achieve a structure with...
Article
The UV excited emission properties of mesoporous silica in the blue and UV range are modified by the adsorption and desorption of oxygen molecules at the two defect sites. To interpret the experimental purging cycles we model the oxygen-silica interaction at thermodynamic level, succeeding in explaining the interaction mechanism and the trend of UV...
Article
Aluminium silicate crystal is proposed as new promising inert matrix as host of luminescent ions. In particular, we studied the luminescence properties of single doped and multi-doped Al2SiO5 samples (doping elements: Ce, Tb, Cr, Fe, Zr) to explore their suitability as phosphors in modern lighting systems. The Al2SiO5 host matrix, obtained in nano-...
Article
Rare earth based phosphors are largely the most applied luminescent materials in the present lightening devices. Their ubiquity in lighting system, like light emitting diodes or compact fluorescent lamps, is related to the optical high efficiency of the rare earth as luminescent ions but also to the relative easiness of growth technique as well hig...
Article
Graphitic carbon nitride (g-C3N4) is considered as one of the most promising photocatalysts for environmental improvement and energy storage. It presents a graphene – like 2D structure, composed of heptazine units connected by amino groups. Here we report multi-technique experimental data (XRD patterns, Raman, steady-time and time resolved Luminesc...
Article
A facile and ecofriendly strategy to project and engineering new organic white LED is tested. The hybrid system was implemented by combining a commercial blue LED, with emission at 405 nm, with an hybrid transparent organic film (Polycarbonate, PMMA, PVC) containing two selected organic dyes. The emitting molecules, a home designed push-pull based...
Article
The luminescence properties of Tb and Ce in Rare Earth Doped crystalline oxides largely depend on their relative concentrations: by increasing the dopant concentration, the luminescence profile changes from blue to green because of the energy transfer among centers. The kinetic properties of the luminescence of optically excited Terbium–Cerium co-d...
Article
Full-text available
The phenomenon of luminescence enhancement was studied in melamine-Y2O3:Tb hybrids. Terbium doped Y2O3 mesoporous nanowires were synthesized by hydrothermal method. X-ray diffraction patterns and Raman scattering spectra testified the realization of a cubic crystal phase. Organic-inorganic melamine-Y2O3:Tb3+ hybrid system was successfully obtained...
Article
The light induced structural phase transition of TiO2 nanoparticles from anatase to rutile structure is reported with different distribution of defect related surface states. Pristine, defective, and surface passivated samples were irradiated in vacuum condition by intragap visible wavelength to achieve the phase transformation. The surface states...
Article
Cerium doped rare earths aluminum perovskites, (REAlO3) are widely used as highly efficient and fast scintillators matrix for γ-ray detection. The crystal structures of pure perovskites (YAlO3 (YAP) and LuAlO3 (LuAP)) and their mixed compound (Lu0,7Y0,3AlO3 (LuYAP)) needs to be free of structural defects in order to avoid unwelcome shallow or deep...
Conference Paper
Full-text available
The light induced phase transformation between stable phases of metal oxides nanoparticles is analyzed. The surrounding atmosphere as well as the defect density at the surface play a fundamental role. It has been found that in oxygen poor chamber atmosphere the phase transformation is favored, while the phase transition cannot be achieved if the de...
Article
The structural evolution of γ-Fe2O3 (maghemite) in bare nanoparticles and in core/shell γ-Fe2O3/SiO2 systems was studied as a function of laser irradiation and heat treatment by the combined use of Raman spectroscopy, transmission electron microscopy, X-ray diffraction. The study was addressed to deepen understanding the driving mechanisms at the b...
Article
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In this work we reveal the structure of a NaYO2 compound solved from the X-ray diffraction powder pattern using the “ab-initio” structure solution approach. The compound turned out to be of trigonal structure, S. G. R-3m isomorphous with α-NaFeO2 layered compound. The lattice parameters are a = 3.404 and c = 16.602 Å, respectively, the atoms being...
Article
The light-induced phase transition of TiO2 nanoparticles from anatase to rutile structure is reported depending on the surrounding environment, the transition being accomplished under oxygen-poor conditions. The transition mechanism is interpreted in the framework of oxygen adsorption and desorption phenomena with the involvement of surface oxygen...
Article
Full-text available
The optical and structural properties of sol–gel prepared polycrystalline films of Cerium doped Lutetium and Yttrium oxyorthosilicates (Ce:LYSO) are investigated by means of optical spectroscopy, XRD diffraction and Raman spectroscopy. The sol–gel samples are compared to commercially available Ce-doped LYSO single crystals, and a detailed study of...
Article
Full-text available
The optical properties of sol–gel prepared Cerium doped Lutetium and Yttrium oxyorthosilicates are investigated in the vacuum ultraviolet energy range by means of synchrotron radiation. The excitation and emission properties are compared to commercial samples grown by Czochralski method. The sol gel polycrystals do show emission features comparable...

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