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Electrospray deposition (ESD) for the fabrication of multilayered (ML) bulk heterojunction polymeric solar cells via direct/inverted configurations was investigated. The active layer heterojunction (P3HT/PCBM) is deposited both in single and multilayered architectures. In ML configuration, the P3HT/PCBM blend film is sandwiched between thin donor (P3HT) and acceptor (PCBM) layers. In ZnO-based inverted solar cells, ZnO film synthesized by sol–gel process was deposited on ITO substrate using spin coatinng. Solar cells were fabricated via ESD and spin coating and the device’s performance parameters were compared. Higher efficiency was obtained in the case of (ML) ESD device (direct structure). Post thermal treatment showed that ESD devices exhibit a power conversion efficiency (PCE) of 1.85% ML and 1.64% SL in direct structure while in the case of inverted structure PCEs of 1.30% ML and 0.82% SL were obtained as compared to 1.64% from the spin coated device at 120°C. The ML ESD devices have shown an overall efficiency enhancement of 13% (direct) and 58% (inverted) over the single layer (SL) ESD devices. The enhanced performance in ML devices is because there is a spatially uninterrupted pathway to the charge carrier transport towards their respective electrodes.

The exploitation into new materials of even the smallest scraps of textiles would contribute to their possible success in sectors such as the automotive industry. In this work, alkaline treatment with low sodium hydroxide (NaOH) concentrations was applied to flax and hemp textile residues, aiming to determine the most suitable process conditions as a function of the quality of the treated fibres. Several parameters were considered: the temperature and the concentration of the alkaline solution and the immersion time in the alkaline solution and, eventually, in distilled water during the neutralization phase. Drying tests were carried out under controlled temperature conditions to assess the effects of the various treatment parameters. The effects of the various procedures were elucidated by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD) to assess crystallinity, atomic force microscopy (AFM) to characterize surface roughness, and nitrogen absorption/desorption cycles to determine how microporosity develops with treatment. It is suggested that only the 1.5 wt./vol.% treatment produced some worthwhile modifications of the fibres to prepare them for their use in composites, more evidently in flax than in hemp, though care needs to be taken about fibre embrittlement and potential water permeability.

In this study, a green and facile thermal reduction of graphene oxide using an eco-friendly system of d-(+)-glucose and NH4OH for the preparation of reduced graphene oxide was described. The obtained reduced graphene oxide dispersion was characterized by SEM, Dynamic Light Scattering, Raman and X-Ray Photoelectron Spectroscopy. TiO2 nanoparticles and reduced graphene oxide nanocomposites were successively prepared and used in the preparation of heterogeneous photocatalysts that were characterized by Atomic Force Microscopy and Photoluminescence Spectroscopy and subsequently tested as visible light photocatalysts for the photodegradation of Alizarin Red S in water as target pollutant. Obtained results of photocatalytic tests regarding the visible light photocatalytic degradation of Alizarin Red S demonstrated that the use of reduced graphene oxide in combination with TiO2 led to a significant improvement for both adsorption of Alizarin Red S on the catalyst surface and photodegradation efficiencies when compared to those obtained with not doped TiO2.

The modifications in the electronic properties induced by the thickness and size of an individual flake of transition-metal halides on different substrates (silicon oxide or In-doped tin oxide) are of particular technological interest, even more in the case of chromium trihalides (CrX3, X = Cl, Br, and I), whose longer lifetime under ambient conditions is particularly intriguing. By using synchrotron-based scanning photoelectron microscopy with a resolution of 0.1 μm and Kelvin probe force microscopy, we evaluated the surface modification reaction and the surface potential. Our results established the correlations of the two latter properties with the thickness of flakes, observing a natural tendency to preserve their characteristic when the flakes have significantly less thickness. This is in contrast to thicker flakes, which show alteration patterns similar to those observed in bulk-cleaved samples (Kazim, S.; Mastrippolito, D.; Moras, P.; Jugovac, M.; Klimczuk, T.; Ali, M.; Ottaviano, L.; Gunnella, R. Phys. Chem. Chem. Phys.2023, 25, 3806–3814. https://doi.org/10.1039%2FD2CP04586A%29. This preliminary study investigates interfaces made by dry transfer of CrCl3 flakes in an atmospheric environment. Cl vacancies and the formation of O/CrCl3 are induced, serving as dissociation centers that facilitate the migration of Cl vacancies between the top and bottom surfaces. By manipulating 2D atomic layers via surface oxidation or the introduction of surface vacancies, a novel and versatile approach is unveiled for the development of low-dimensional multifunctional nanodevices.

Graphene oxide (GO) is a promising material for the development of cost-effective detection systems. In this work, we have devised a simple and rapid GO-based method for the sequence-specific identification of DNA molecules generated by PCR amplification. The csp genes of Escherichia coli, which share a high degree of sequence identity, were selected as paradigm DNA templates. All tested csp genes were amplified with unlabelled primers, which can be rapidly removed at the end of the PCR taking advantage of the preferential binding to GO of single-stranded versus duplex DNA molecules. The amplified DNAs (targets) were heat-denatured and hybridized to a fluorescently-labelled single strand oligonucleotide (probe), which recognizes a region of the target DNAs displaying sequence variability. This interaction is extremely specific, taking place with high efficiency only when target and probe show perfect or near perfect matching. Upon GO addition, the unbound fraction of the probe was captured and its fluorescence quenched by the GO's molecular properties. On the other hand, the probe-target complexes remained in solution and emitted a fluorescent signal whose intensity was related to their degree of complementarity.

The effect of surface modification using ascorbic acid as a surface modifier of nano-TiO2 heterogeneous photocatalyst was studied. The preparation of supported photocatalyst was made by a specific paste containing ascorbic acid modified TiO2 nanoparticles used to cover Polypropylene as a support material. The obtained heterogeneous photocatalyst was thoroughly characterized (scanning electron microscope (SEM), RAMAN, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and Diffuse Reflectance Spectra (DRS) and successfully applied in the visible light photodegradation of Alizarin Red S in water solutions. In particular, this new supported TiO2 photocatalyst showed a change in the adsorption mechanism of dye with respect to that of only TiO2 due to the surface properties. In addition, an improvement of photocatalytic performances in the visible light photodegration was obtained, showing a strict correlation between efficiency and energy band gap values, evidencing the favorable surface modification of TiO2 nanoparticles.

Structural and electronic properties of silicon nanowires with pre-designed structures are investigated. Wires with distinct structure were investigated via advanced spectroscopic techniques such as X-ray absorption spectroscopy and Raman scattering as well as transport measurements. We show that wire structures can be engineered with metal assisted etching fabrication process via the catalytic solution ratios as well as changing doping type and level. In this way unique well-defined electronic configurations and density of states are obtained in the synthesized wires leading to different charge carrier and phonon dynamics in addition to photoluminescence modulations. We demonstrate that the electronic properties of these structures depend by the final geometry of these systems as determined by the synthesis process. These wires are characterized by a large internal surface and a modulated DOS with a significantly high number of surface states within the band structure. The results improve the understanding of the different electronic structures of these semiconducting nanowires opening new possibilities of future advanced device designs.

In this work, the characteristic structure of keratin extracted from two different kinds of industrial waste, namely sheep wool and chicken feathers, using the sulfitolysis method to allow film deposition, has been investigated. The structural and microscopic properties have been studied by means of scanning electron microscopy (SEM), Raman spectroscopy, atomic force microscopy (AFM), and infrared (IR) spectroscopy. Following this, small-angle X-ray scattering (SAXS) analysis for intermediate filaments has been performed. The results indicate that the assembly character of the fiber can be obtained by using the most suitable extraction method, to respond to hydration, thermal, and redox agents. The amorphous part of the fiber and medium range structure is variously affected by the competition between polar bonds (reversible hydrogen bonds) and disulfide bonds (DB), the covalent irreversible ones, and has been investigated by using fine structural methods such as Raman and SAXS, which have depicted in detail the intermediate filaments of keratin from the two different animal origins. The preservation of the secondary structure of the protein obtained does offer a potential for further application of the waste-obtained keratin in polymer films and, possibly, biocomposites.

Improvements in sodium intercalation in sodium cathodes have been debated in recent years. In the present work, we delineate the significant effect of the carbon nanotubes (CNTs) and their weight percent in the intercalation capacity of the binder-free manganese vanadium oxide (MVO)-CNTs composite electrodes. The performance modification of the electrode is discussed taking into account the cathode electrolyte interphase (CEI) layer under optimal performance. We observe an intermittent distribution of the chemical phases on the CEI, formed on these electrodes after several cycles. The bulk and superficial structure of pristine and Na+ cycled electrodes were identified via micro-Raman scattering and Scanning X-ray Photoelectron Microscopy. We show that the inhomogeneous CEI layer distribution strongly depends on the CNTs weight percentage ratio in an electrode nano-composite. The capacity fading of MVO-CNTs appears to be associated with the dissolution of the Mn2O3 phase, leading to electrode deterioration. This effect is particularly observed in electrodes with low weight percentage of the CNTs in which the tubular topology of the CNTs are distorted due to the MVO decoration. These results can deepen the understanding of the CNTs role on the intercalation mechanism and capacity of the electrode, where there are variations in the mass ratio of CNTs and the active material.

Improvements in sodium intercalation in sodium cathodes have been debated in recent years. In the present work, we delineate the significant effect of the carbon nanotubes (CNTs) and their weight percent in the intercalation capacity of the binder-free manganese vanadium oxide (MVO)-CNTs composite electrodes. The performance modification of the electrode is discussed taking into account the cathode electrolyte interphase (CEI) layer under optimal performance. We observe an intermittent distribution of the chemical phases on the CEI, formed on these electrodes after several cycles. The bulk and superficial structure of pristine and Na[sup.+] cycled electrodes were identified via micro-Raman scattering and Scanning X-ray Photoelectron Microscopy. We show that the inhomogeneous CEI layer distribution strongly depends on the CNTs weight percentage ratio in an electrode nano-composite. The capacity fading of MVO-CNTs appears to be associated with the dissolution of the Mn[sub.2] O[sub.3] phase, leading to electrode deterioration. This effect is particularly observed in electrodes with low weight percentage of the CNTs in which the tubular topology of the CNTs are distorted due to the MVO decoration. These results can deepen the understanding of the CNTs role on the intercalation mechanism and capacity of the electrode, where there are variations in the mass ratio of CNTs and the active material.