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The tailoring of multi-tasking perovskite oxide-based electrodes for solid oxide cells has shown growing interest. The development of flexible structures represents a crucial step towards the design of symmetric and possibly SOFC/SOEC reversible systems. In this work, low (0.5 mol%) B-site Pt-doping in a lanthanum strontium ferrite is presented as a successful approach to enhance the parent perovskite properties as both SOC air and fuel electrode. Structural, morphological and electrochemical characterizations of La0.6Sr0.4Fe0.995Pt0.005O3-δ (LSFPt005) are provided and compared to the undoped compound. LSFPt005-symmetric devices are tested as CO-SOFCs and CO2-SOECs at 850 °C, respectively, obtaining a maximum power density of 301 mW/cm2 and a current density of 0.82 A/cm2 at 1.5 V. Insights of cell operating mechanisms are provided through electrochemical impedance spectroscopy.

Due to global environmental concerns related to climate change, the need to improve the service life of structures and infrastructures is imminently urgent. Structural elements typically suffer service life reductions, leading to poor environmental sustainability and high maintenance costs. Graphene oxide nanosheets (GONSs) effectively dispersed in a cement matrix can promote hydration, refine the microstructure and improve interfacial bonding, leading to enhanced building materials’ performance, including mechanical strength and transport properties. Cement-based nanocomposites engineered with GONSs were obtained using two commercial nanofillers, a GO water suspension and a free-flowing GO nanopowder, characterized by fully comparable morphology, size and aspect ratio and different oxidation degrees (i.e., oxygen-to-carbon molar ratio), 0.55 and 0.45, respectively. The dosage of the 2D-nanofiller ranged between 0.01% and 0.2% by weight of cement. The electrical and thermal properties were assessed through electrochemical impedance spectroscopy (EIS) and a heat flow meter, respectively. The results were discussed and linked to micrometric porosity investigated by micro-computed tomography (μ-CT) and transport properties as determined by initial surface absorption test (ISAT), boil-water saturation method (BWS) and chloride ion penetration test. Extra-low dosage mortars, especially those loaded with a lower oxidation degree (i.e., 0.45GO), showed decreased permeability and improved barrier to chloride ion transport combined with enhanced thermal and electrical conductivity with respect to that of the control samples.

The carbon dioxide highly sensitive ultra-thin optical sensor using plasmonic nanoparticles distributed uniformly on the nanowall honeycomb structure with a footprint in the millimeter range is presented in this work. The zinc oxide (ZnO) honeycomb nanowall structure is grown by the pulsed laser deposition (PLD) method. Moreover, the performance of the fabricated structure as a gas nanosensor is simulated using the finite difference time domain (FDTD) method in the visible and near-infrared regions. A graphene layer is mounted on the top of the nanowall, and then, plasmonic nanoparticles are distributed on the nanowall sides. Furthermore, the effect of gas concentration on the pressure and consequently on the dielectric constant of the gas are also illustrated in this article. Red-shift in the absorption has been noticed with different refractive indices and intensity sensitivities. The obtained refractive index sensitivity of the proposed nano optical sensor is 874 nm/RIU, and the intensity sensitivity is 5,174 RIU−1 with the figure of merit of 12.5 and quality factor (Q-factor) of 281 at a carbon dioxide (CO2) concentration of 5,500 ppm. Finally, the absorbed power of the incident light is calculated using different polarization angles, from 10° to 80° with a step10°.

Solid oxide fuel cells (SOFCs) have a great potential among the emerging energy conversion technologies because they can efficiently convert various types of fuel (hydrogen, methane, CO, biogas) into electrical energy in the 750-850 °C temperature range. The choice of electrodes remains a challenge because most metal oxides suffer from low chemical stability and low electrocatalytic activity toward oxygen reduction reaction (ORR) in the intermediate temperatures (IT) range (500-700 °C) [1]. In this view, perovskite oxides (ABO3) have shown excellent properties in terms of thermal stability, compatibility with other cell components, low production cost and, most importantly, great flexibility [1]. La0.6Sr0.4FeO3-δ, (LSF) perovskite oxide have been widely investigated for the high electrical conductivity and the electrochemical properties [2]. However, the main drawback is the poor activity towards ORR in the IT range, as most iron-based perovskite oxides [3]. The B-site doping with noble metal catalysts can sensitively improve the properties and make the compounds suitable for electrode application. The addition of small amounts of Ru or Pt into LSF structure can be an effective approach to improve the electrocatalytic properties [4,5]. Specifically, we synthesized B-site doped LSF powders with very low amounts (15 m2/g). All compounds showed a single perovskite phase. As reported in Fig. (a), the addition of Ru and Pt in the structure causes a progressive shift of the XRD peaks to lower 2θ angles indicating the perovskite lattice expansion due to the substitution of Fe4+/ Fe3+ sites with larger Ru and Pt ions. To assess the electrocatalytic activity, the compounds were investigated in oxidizing conditions using electrochemical impedance spectroscopy (EIS) analysis. Fig. (b) shows the Arrhenius plot of area specific resistance (ASR) values of LSFRu and LSFPt perovskite oxides. The ASR values were measured on LSFM/La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM)/LSFM (M=Ru, Pt) symmetric cells in the temperature range 550-800 °C. The insertion of a very low amount (1%mol) of Pt or Ru significantly reduces the polarization resistance, confirming the beneficial effect of noble metal ions on ORR activity. All these features suggest that very low Pt and Ru doping positively affects the structural and electrocatalytic properties valuably for cathodic applications. [1] Hwang J, Rao R.R. (2017). Science 358:751-756 [2] Hansen KK, Mogensen M (2008). ECS Trans 13:153–160 [3] Chavan SV, Singh RN (2013). J Mater Sci 48:6597–6604 [4] Fan W, Sun Z. (2016) RSC Adv 6:34564 [5]Shaoli G., Hongjing Wu, (2015),Catalysts, 5, 366-391 Figure 1

The low-cost material extrusion (MEX) additive manufacturing technology can offer an economical alternative to manufacture metal parts with complex geometry over traditional manufacturing or the more expensive powder bed fusion (PBF) techniques. In this work, a feedstock made of 316L stainless steel powder (65 % by volume) and a single component binder (LDPE) system was developed. The use of a single binder rather than two or more components, commonly used in metal MEX, introduces a novel and more sustainable solution in terms of costs and less use of chemicals. The rheology and processability of the feedstocks were studied, and samples were 3D printed. Debinding and sintering under a hydrogen atmosphere at 1380 °C were performed, and the resulting metallic parts have been characterized by a mechanical and microstructural point of view. The results show a sintered steel having 93 % of the theoretical density and an austenitic phase confirming that the post-processing under reductive atmosphere protected the samples from oxidation and other contamination. The sintered 3D parts show a grain size of ∼ 45 μm, a yield point of 250 MPa, a tensile strength of 520 MPa, and a Vickers microhardness of 285 HV typical of annealed steel.

Two-dimensional (2D) materials are used in energy storage and conversion due to their unique electronic structure and large specific area. In this work, 2D vanadium carbide (V2CTx MXene) is fabricated and studied as an efficient and earth-abundant electrocatalyst for electrocatalytic N2 reduction reaction (NRR). When tested in 0.1 M Na2SO4, such electrocatalyst achieves a large NH3 yield rate of 12.6 μg h–1 mg–1cat. and a Faradaic efficiency of 4% at –0.7 V vs. reversible hydrogen electrode. Theoretical calculations show a low reaction barrier of 0.88 eV in the distal route for this catalyst.

Nitrogen can be electrochemically reduced to produce ammonia, which supplies an energy-saving and environmental-benign route at room temperature, but high-efficiency catalysts are sought to reduce the reaction barrier. Here, iron-doped α-MoO3 nanosheets are thus designed and proposed as potential catalysts for fixing N2 to NH3. The α-MoO3 band structure is intentionally modulated by the iron doping, which narrows the band gap of α-MoO3 and turns the semiconductor into a metal-like catalyst. Oxygen vacancies, generated by substituting Mo6+ for Fe3+ anions, are beneficial for nitrogen adsorption at the active sites. In 0.1 M Na2SO4, the Fe-doped MoO3 catalyst reached a high faradaic efficiency of 13.3% and an excellent NH3 yield rate of 28.52 μg h-1 mgcat-1 at -0.7 V versus reversible hydrogen electrode, superior to most of the other metal-based catalysts. Theoretical calculations confirmed that the N2 reduction reaction at the Fe-MoO3 surface followed the distal reaction path.

The design and fabrication of highly efficient oxygen evolution reaction (OER) electrocatalysts is crucial for further development of electrochemical conversion devices. In this paper, the pulsed l...

Mechanical performance of 3D printed ‘Rubber-like’ commercial resins are not comparable to typical vulcanized diene rubbers since they show lower strain at break. In the present work, samples made of liquid butadiene rubber have been photocured by thiol-ene chemistry and 3D printed. Morphological features and mechanical properties have been investigated by means of scanning electron microscopy (SEM), dynamic mechanical analysis (DMA) and tensile tests. The 3D printed samples show the characteristic mechanical properties of unfilled diene rubbers reaching a strain at break up to 400%.

The main purpose of the present work is to analyze a series of Ag nanoparticles (NPs) with different size or ligand functionalization by using X-ray photoelectron spectroscopy (XPS) and to identify the differences in the band-shape and energy peak position of photoemission spectra due to the particle dimension. A transmission electron microscopy characterization was performed, to verify the consistency of the results. Three types of samples were prepared starting from AgNO3 water solution and adding different capping agents. In the first two cases, the formation of NPs was promoted by the reduction of silver ions Ag+1 to metallic Ag-0 through the addition of sodium borohydride, whereas in the last case, it was triggered by the exposure to UV light. Depending on the size of the NPs, a different physical behavior can be recognized. NPs with diameter of about 5 nm are characterized by the phenomenon of localized surface plasmon resonance (LSPR). The other type of samples having a diameter of about 1.5 nm presents discrete energy levels instead of electronic bands, and in this case, a typical fluorescence phenomenon can be observed. In the latter case, we can refer to such systems as nanoclusters. The XPS analyses were focused on the Ag 3D spectra looking for the possible shifts of the Ag doublet as a function of the particles size. The ultraviolet photoelectron spectroscopy with He II source was used for the investigation of possible changes in the valence band.

Electrocatalytic nitrogen reduction reaction (ENRR) offers a carbon-neutral process to fix nitrogen into ammonia, but its feasibility depends on the development of highly efficient electrocatalysts. Herein, we report that Fe ion grafted on MoO3 nanorods synthesized by an impregnation technique can efficiently enhance the electron harvesting ability and the selectivity of H+ during the NRR process in neutral electrolyte. In 0.1 M Na2SO4 solution, the electrocatalyst exhibited a remarkable NRR activity with an NH3 yield of 9.66 μg h−1 mg−1cat and a Faradaic efficiency (FE) of 13.1%, far outperforming the ungrafted MnO3. Density functional theory calculations revealed that the Fe sites are major activation centers along the alternating pathway.

This work focuses on the replacement of mineral oils with bio-based waste cooking oils in rubber compounding. Two different waste cooking oils from potatoes and chicken frying process were analyzed by means of chemical and rheological tests to evaluate the chemical composition, the oxidative stability and the viscosity. Waste oils have been introduced in elastomeric compounds as substitute for typical processing aids (i.e. lubricants). Cure kinetics of rubber compounds was studied by rheological characterization. Mechanical properties of vulcanized samples were determined by means of tensile tests, hardness tests and dynamic mechanical analysis. The waste oils showed a rheological behavior very similar to the mineral oils conventionally employed in rubber manufacturing leading to almost the same processability of the resulting compound. The waste oils did not significantly affect the vulcanization kinetics of the rubber compound, as expected for conventional lubricants. Waste cooking oils and mineral oil show analogous influence on mechanical properties of cured compounds. At increasing oil content, the elongation at break and the tensile strength increased whereas the values of Elastic Modulus at 100% strain, the Storage Modulus and Shore A Hardness decreased with respect to the oil-free sample. These results are very promising, confirming the possibility to replace the mineral oils, in a good practice of circular economy.

Highly performing perovskite-based anodes for methane mixtures-fueled solid oxide fuel cells (SOFC) are proposed. Catalytic activities of La0.6Sr0.4Fe1-xPdxO3-δ (LSFPd) with x = 0.05, 0.1 toward dry reforming of methane (DMR) and partial oxidation of methane (POM) reactions are investigated. The addition of (30wt%) Ce0.85Gd0.15O2-δ (GDC) and of (30wt%) Ni(5wt%)-GDC to the perovskite compounds was evaluated to enhance both electrocatalytic and electrochemical properties. Electrolyte-supported cells based on La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM) pellets and LSFPd perovskite oxides at both electrodes are fabricated and tested using CH4, CH4/Ar and CH4/CO2 mixtures in the 750–850°C temperature range. Fuel cell tests using anodic mixtures such as LSFPd/GDC and LSFPd/Ni-GDC are also performed. A discussion based on the comparison between catalytic and electrochemical results and on the possible reforming and/or oxidation reactions taking place at the anode is detailed.

With the aim of presenting the processes governing the Laser-Induced Periodic Surface Structures (LIPSS), its main theoretical models have been reported. More emphasis is given to those suitable for clarifying the experimental structures observed on the surface of wide bandgap semiconductors (WBS) and dielectric materials. The role played by radiation surface electromagnetic waves as well as Surface Plasmon Polaritons in determining both Low and High Spatial Frequency LIPSS is briefly discussed, together with some experimental evidence. Non-conventional techniques for LIPSS formation are concisely introduced to point out the high technical possibility of enhancing the homogeneity of surface structures as well as tuning the electronic properties driven by point defects induced in WBS. Among these, double- or multiple-fs-pulse irradiations are shown to be suitable for providing further insight into the LIPSS process together with fine control on the formed surface structures. Modifications occurring by LIPSS on surfaces of WBS and dielectrics display high potentialities for their cross-cutting technological features and wide applications in which the main surface and electronic properties can be engineered. By these assessments, the employment of such nanostructured materials in innovative devices could be envisaged.

Apoptotic cells stimulate compensatory proliferation through the caspase-3-cPLA-2-COX-2-PGE-2-STAT3 Phoenix Rising pathway as a healing process in normal tissues. Phoenix Rising is however usurped in cancer, potentially nullifying pro-apoptotic therapies. Cytotoxic therapies also promote cancer cell plasticity through epigenetic reprogramming, leading to epithelial-to-mesenchymal-transition (EMT), chemo-resistance and tumor progression. We explored the relationship between such scenarios, setting-up an innovative, straightforward one-pot in vitro model of therapy-induced prostate cancer repopulation. Cancer (castration-resistant PC3 and androgen-sensitive LNCaP), or normal (RWPE-1) prostate cells, are treated with etoposide and left recovering for 18 days. After a robust apoptotic phase, PC3 setup a coordinate tissue-like response, repopulating and acquiring EMT and chemo-resistance; repopulation occurs via Phoenix Rising, being dependent on high PGE-2 levels achieved through caspase-3-promoted signaling; epigenetic inhibitors interrupt Phoenix Rising after PGE-2, preventing repopulation. Instead, RWPE-1 repopulate via Phoenix Rising without reprogramming, EMT or chemo-resistance, indicating that only cancer cells require reprogramming to complete Phoenix Rising. Intriguingly, LNCaP stop Phoenix-Rising after PGE-2, failing repopulating, suggesting that the propensity to engage/complete Phoenix Rising may influence the outcome of pro-apoptotic therapies. Concluding, we established a reliable system where to study prostate cancer repopulation, showing that epigenetic reprogramming assists Phoenix Rising to promote post-therapy cancer repopulation and acquired cell-resistance (CRAC).

Copyright: © 2021 by the authors. The impact of extra-low dosage (0.01% by weight of cement) Graphene Oxide (GO) on the properties of fresh and hardened nanocomposites was assessed. The use of a minimum amount of 2-D nanofiller would minimize costs and sustainability issues, therefore encouraging the market uptake of nanoengineered cement-based materials. GO was characterized by X-ray Photoelectron Spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), Atomic Force Microscopy (AFM), X-ray Diffraction (XRD), and Raman spectroscopy. GO consisted of stacked sheets up to 600 nm × 800 nm wide and 2 nm thick, oxygen content 31 at%. The impact of GO on the fresh admixtures was evaluated by rheology, flowability, and workability measurements. GO-modified samples were characterized by density measurements, Scanning Electron Microscopy (SEM) analysis, and compression and bending tests. Permeability was investigated using the boiling-water saturation technique, salt ponding test, and Initial Surface Absorption Test (ISAT). At 28 days, GO-nanocomposite exhibited increased density (+14%), improved compressive and flexural strength (+29% and +13%, respectively), and decreased permeability compared to the control sample. The strengthening effect dominated over the adverse effects associated with the worsening of the fresh properties; reduced permeability was mainly attributed to the refining of the pore network induced by the presence of GO.

In this paper, a hybrid commercially available alumina/polymer filament was 3D printed and thermally treated (debinding and sintering) to obtain ceramic parts. Microscopic and spectroscopic analysis was used to thoroughly characterize the green and sintered parts in terms of their mesostructured, as well as their flexural properties. The sintered samples show an α alumina crystalline phase with a mean density of 3.80 g/cm3, a tensile strength of 232.6 ± 12.3 MPa, and a Vickers hardness of 21 ± 0.7 GPa. The mean thermal conductivity value at room temperature was equal to 21.52 ± 0.02 W/(mK). The values obtained through FFF production are lower than those obtained by conventional processes as the 3D-printed samples exhibited imperfect interlayer bonding and voids similar to those found in the structures of polymeric FFFs. Nonetheless, the highly filled ceramic filament is suitable for use in affordable and easy-to-operate FFF machines, as shown by the cost analysis of a real printed and sintered FFF part.

Boron nitride nano-platelets have been functionalized with oleylamine using a simple method without ultrasonication. The functionalization is effective with the formation of a coordination bonds between the boron nitride nano-platelets and the oleylamine molecules. The oleylamine functionalization allows for the production of 25% by weight loaded polyamide 6 – boron nitride composites having higher mechanical properties (15% tensile strength increase) and better through-plane thermal conductivity (0.85 to 0.99 W/m·K) with respect to the untreated samples. A better particle-matrix interaction is confirmed by SEM imaging and rheological analysis. The injection moulding process determines a filler orientation which influences the thermal conductivity.

Immiscible blends of ethylene‐propylene‐diene‐monomer (EPDM) and polyoxymethylene (POM), when EPDM is the major phase were compatibilized on the addition of an ionomer, poly(ethylene‐co‐methacrylic acid). The inclusion of the ionomer reduced the interfacial tension between the two phases, such that the diameter of the POM domains were significantly reduced to between 0.5 and 2 μm, typical of that required to toughen ductile polymers. The mechanical properties of the resultant compatibilized blends were significantly enhanced with increases in Young's modulus (↑54%), tensile strength (σ, ↑139%), elongation at break (e, ↑97%), and tensile toughness (↑500%) with increasing ionomer content, relative to EPDM rubber alone. The ShoreA hardness of the compatibilized blend was 70.1 compared with 56.8 for the immiscible binary blend and, 50.2 for neat EPDM rubber.

The impact of graphite nanoplatelets (GNPs) on the physical and mechanical properties of cementitious nanocomposites was investigated. A market-available premixed mortar was modified with 0.01% by weight of cement of commercial GNPs characterized by two distinctively different aspect ratios. The rheological behavior of the GNP-modified fresh admixtures was thoroughly evaluated. Hardened cementitious nanocomposites were investigated in terms of density, microstructure (Scanning Electron Microscopy, SEM and micro–Computed Tomography, μ-CT), mechanical properties (three-point bending and compression tests), and physical properties (electrochemical impedance spectroscopy, EIS and thermal conductivity measurements). At 28 days, all GNP-modified mortars showed about 12% increased density. Mortars reinforced with high aspect ratio GNPs exhibited the highest compressive and flexural strength: about 14% and 4% improvements compared to control sample, respectively. Conversely, low aspect ratio GNPs led to cementitious nanocomposites characterized by 36% decreased electrical resistivity combined with 60% increased thermal conductivity with respect to the control sample.

Reversible solid oxide cell (RSOC) technology allows use of a single device to efficiently derive chemicals from power (power-to-fuel) and power from chemicals (fuel-to-power). Fuel flexibility is a key aspect, as developing SOCs able to operate on fuels other than hydrogen can ease their integration into existing infrastructure. In addition, H2O and/or CO2 reduction is favorable in SOECs as polarization losses are reduced at high temperature. Here, a composite fuel electrode, 60 wt.% La0.6Sr0.4Fe0.8Mn0.2O3-δ (LSFMn) and 40 wt.% (5 wt.% Ni)-containing Ce0.85Sm0.15O2-δ (Ni-SDC) was investigated in H2-fueled, CO-fueled SOFCs and for CO2 reduction in SOEC mode. In reducing conditions, Fe exsolved from the LSFMn perovskite formed a Ni-Fe alloy with Ni present on SDC. The composite fuel electrode showed remarkable activity for CO2 reduction with a current density output of 1.40 A cm-2 (1.5 V) at 850 °C. SOFC/SOEC cell reversibility was obtained in different CO2:CO mixtures. Electrochemical impedance spectroscopy analysis was used to better understand cell mechanisms in SOFC and SOEC mode.

Processing biological materials with 3-dimensional (3D) printers has attracted increasing interest in several research areas. At the same time, off-the-shelf solutions are increasingly available in a wider variety to meet the current market demand. However, most of the available bioprinters are closed source, thus, modifications are quite challenging or require an avoidable consultation process with the manufacturer. Furthermore, the entry prices for basic machines amount to several thousands of euros. Whereas, high-end 3D bio printers with a vast array of features are available for several hundred thousand euros. Due to the immense potential of this tool in the field of biotechnology it is important to extend the availability of this technology for research purposes in terms of adaptability and price. This ongoing work focuses on open-source 3D printer heads with the ability to extrude biological materials. The print heads include several techniques to process low as well as high viscose biomaterials such as agar and gelatin. Additionally, obstacles such as continuous substrate tempering or integration into existing 3D printers are addressed. The work presented is open source and thus freely adaptable to any user’s specific needs. Our goal is to process a diverse range of biomaterials with different print techniques.

Thin films based on aluminum nitride were obtained by fs-laser assisted Pulsed Laser Deposition (fs-PLD) at room temperature on tantalum substrates for studying the electron emission performance in the temperature range 700- 1600 °C, so to investigate the possibility of their exploitation as thermionic cathodes. Results of structural, chemical and morphological analyses show the growth of nanostructured thin films with a significant oxygen contamination, forming a mixture of crystalline aluminum nitride and aluminum oxide as well as metallic aluminum inclusions. Despite the considerable presence of oxygen, the developed cathodes demonstrate to possess promising thermionic emission characteristics, with a work function of 3.15 eV, a valuable Richardson constant of 20.25 A cm−2K−2, and a highly thermo- electronic stability up to operating temperatures of 1600 °C.

Strain monitoring is of great interest in order to check components structural life, to prevent catastrophic failures, and, possibly, to predict residual life in case of unexpected events. In this study, strain sensing epoxy-based coatings containing carbon nanotubes (MWCNTs), graphene nanoplatelets (GNPs), and a mix of the two (MWCNT+GNP) have been produced, with the same initial electrical resistivity, and applied on glass fiber reinforced composites. Morphological, mechanical, and electrical tests have been then performed evaluating the resistance variation and the strain sensing performance of the sensors. A theoretical model to relate the resulting gauge factors to the different types of nanofillers has been applied. The results showed that all systems present a strain sensing performance with different gauge factors (and hence sensitivity) at low strain: GNP samples showed the highest gauge factor (10.3), MWCNT samples the lowest (1.5), and the mixed system lies in the middle (4.3). From analytical analysis, the value of initial distance among conductive particles was found to be 0.3 nm in the case of MWCNT and 1.2 nm for GNP, explaining why the gauge factors of the produced sensors are different.

Electrocatalytic nitrogen reduction to ammonia has attracted increasing attention as it is more energy-saving and eco-friendly. For this endeavor, the development of high-efficiency electrocatalysts with excellent selectivity and stability is indispensable to break up the stable covalent triple bond in nitrogen. In this study, we report monodisperse Cu clusters loaded on defective ZrO2 nanofibers for nitrogen reduction under mild conditions. Such an electrocatalyst achieves an NH3 yield rate of 12.13 μg h-1 mgcat.-1 and an optimal Faradaic efficiency of 13.4% at -0.6 V versus the reversible hydrogen electrode in 0.1 M Na2SO4. Density functional theory calculations reveal that the N2 molecule was reduced to NH3 at the Cu active site with an ideal overpotential. Meanwhile, the interaction between bonding and antibonding of the Cu-N bond promotes activation of N2 and maintains a low desorption barrier.

Recent improvements in additive layer manufacturing (ALM) have provided new designs of geometrically complex structures with lighter materials and low processing costs. The use of additive manufacturing in spacecraft production is opening up many new possibilities in both design and fabrication, allowing for the reduction of the weight of the structure subsystems. In this aim, polymeric ALM structures can become a choice, in terms of lightweight and demisability, as far as good thermomechanical properties. Moreover, provided that fused-deposition modeling (FDM) is used, nanosats and other structures could be easily produced in space. However, the choice of the material is a crucial step of the process, as the final performance of the printed parts is strongly dependent on three pillars: design, material, and printing process. As a high-performance technopolymer, polyether ether ketone (PEEK) has been adopted to fabricate parts via ALM, however, the space compatibility of 3D-printed parts remains not demonstrated. This work aimed to realize a nanosat polymeric structure via FDM, including all the phases of the development process: thermomechanical design, raw material selection, printing process tuning, and manufacturing of a proof of concept of a technological model. The design phase includes the application of topology optimization to maximize mass saving and take full advantage of the ALM capability. 3D-printed parts were characterized via thermomechanical tests, outgassing tests of 3D-printed parts are reported confirming the outstanding performance of polyether ether ketone and its potential as a material for structural space application.

The electrocatalytic nitrogen reduction reaction (NRR) has been deemed a promising and reliable approach to massively produce ammonia under ambient conditions. A high-efficiency electrocatalyst with an excellent selectivity is highly required to reduce the multiple reaction barriers of N2 + 3H2O → 2NH3 + 1.5O2. Here, we report electrospun zirconia nanofibers as a non-noble NRR electrocatalyst to convert nitrogen to ammonia. Theoretical calculations predict that the Zr sites with oxygen vacancies are favorable for nitrogen adsorption and reduction. Experimentally, the larger concentration of oxygen defects in such an electrocatalyst allowed achieving a NH3 formation rate of 9.63 μg h−1 mgcat.−1 and an optimal faradaic efficiency of 12.1% at −0.7 V vs. the reversible hydrogen electrode in 0.1 M Na2SO4.

Intermittency of renewable energy sources can be profitably faced using efficient energy storage systems. Reversible solid oxide cells (RSOCs) able to operate with carbon-containing species are likely among the most appealing choices. Energy can be obtained by natural gas and/or biogas (SOFC mode), with useful recovery of CO2 in the exhausts. Besides, if the electrode is also active towards CO2 electrolysis (SOEC mode), CO2 is reduced to CO and O2. In this work a composite material with in-situ formed Ni-Fe alloy catalyst consisting of La1.2Sr0.8Fe0.6Mn0.4O4 Ruddlesden-Popper perovskite and Ni-Ce0.85Sm0.15O2-δ fluorite was developed as a multi-functional fuel-electrode for RSOCs. The composite electrode was tested in SOFC mode as anode for hydrogen, dry methane and carbon monoxide oxidation and showed power density outputs of 657, 668 and 527 mW/cm2 at 850 °C, respectively, together with redox stability and coking tolerance for over 120 h. In SOEC mode, it was tested as cathode and delivered 2.66 A/cm2 at 2 V in a 95:5 CO2:CO mixture, retaining a current density of 1 A/cm2 for more than 40 h.

In this work, porous complex and metal-free cathodes based on a (La0.6Sr0.4) (Cr0.5Mn0.5) O3 (LSCM) screen-printed backbone infiltrated with Ce0.9Gd0.1O2 (GDC) were fabricated for solid oxide electrolyzer cells. GDC infiltration has been optimized by structural and microstructural investigation and tested by electrochemical measurements in CO/CO2 mixtures. Infiltrated electrodes with a non-aqueous GDC solution showed the best electro-catalytic activity towards CO2 reduction, exhibiting a much lower polarization resistance, i.e., Rpol = 0.3 Ω&middot, cm2 at 900 &deg, C. The electrochemical performance of LSCM/GDCE in terms of Rpol is comparable to the best-performing Ni-YSZ cathode in the same operating conditions (Rpol = 0.23 Ω&middot, cm2).

Perovskite oxides such as ferrites have been widely investigated for their remarkable electrochemical activity as SOFC electrodes. However, their phase instability in reducing conditions remains an issue for anode application. The role of Mn substitution into B-site of La0.6Sr0.4FeO3-δ (LSF) perovskite oxide was investigated. New insights on the structural evolution of La0.6Sr0.4Fe0.8Mn0.2O3-δ (LSFMn) upon high temperature reduction were revealed. In oxidizing atmosphere, Mn substitution reduces the oxygen vacancy concentration while, switching to reducing conditions, it drives the transition from rhombohedral perovskite to single Ruddlesden-Popper phase, affecting the Fe0 exsolution. Redox-cycles of LSFMn were investigated and the properties of re-oxidized compounds were highlighted. The effect of Mn substitution on perovskite conductivity was also evaluated both in oxidizing and reducing conditions.

Permanent Rare Earth magnets are becoming more and more important in efficient motors and generators with high energy density. Among them NdFeB magnets are the most employed, with NdFeB having higher remanence, high coercivity and energy product. Nevertheless,their poor corrosion resistance makes them susceptible to degradation of the magnetic properties. One possible solution is the development of innovative polymeric composite magnetic materials. The preparation of NdFeB powders filled polymeric matrix (PEEK), with a double goal of protecting the magnetic alloy is proposed, thus preventing it from corrosion, and to realize a new material that can be shaped in the form of filaments. This material was used as feedstock in the 3D printing process to produce high performance magnets with customized and optimized design. The PEEK-NdFeB filaments were produced with three percentages of filler amount(i.e. 25, 50 and 75 wt%). PEEK neat filaments were produced as reference. The influence of the filler on the main thermomechanical properties of the resulting composites, as well as its effect onthe 3D printing process were evaluated by means of different investigation techniques (DSC, DMTA, XRD, tensile testing). The magnetic properties exhibited by Fused Filament Fabrication (FFF) printed parts confirmed the feasibility of employing such a combination of an innovative manufacturing technique and high-performance PEEK-NdFeB compounds.The characterization carried out on both neat and composite filaments evidenced that the presence of the filler slightly decreased the thermal stability, increased the elastic modulus while decreasing ductility and maximum tensile strength. By means of DSC analysis, it was confirmed that the crystallinity is influenced by the presence of the filler. Magnetic measurement performed on the 3D printed parts demonstrate that interesting magnetic properties were achieved, confirming the feasibility of the magnetic 3D printed composite with PEEK.

A structured catalyst for the dry reforming of methane (DRM) was investigated as a biogas pre-reformer for indirect internal reforming solid oxide fuel cell (IIR-SOFC). For this purpose, a NiCrAl open-cell foam was chosen as support and Ni-based samarium doped ceria (Ni-SmDC) as catalyst. Ni-SmDC powder is a highly performing catalyst showing a remarkable carbon resistance due to the presence of oxygen vacancies that promote coke gasification by CO2 activation. Ni-SmDC powder was deposited on the metallic support by wash-coating method. The metallic foam, the powder, and the structured catalyst were characterized by several techniques such as: N2 adsorption-desorption technique, X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), focused ion beam (FIB), temperature programmed reduction (H2-TPR), and Raman spectroscopy. Catalytic tests were performed on structured catalysts to evaluate activity, selectivity, and stability at SOFC operating conditions.

In cultural heritage field, significant research efforts have been recently made to improve the efficacy of anti-vegetative treatments and to reduce the environmental impact caused by biocides high concentration. According to the pro-ecological approach, this work reports a novel approach based on the encapsulation/incorporation of environmentally-friendly biocides in different silica nanosystems in order to control the development of biological patinas on outdoor cultural heritage. Two different green biocides have been selected and tested in silica nanosystems: the zosteric acid sodium salt (ZS), a natural antifoulant compound produced by Zostera marina (eelgrass), and the usnic acid (UA), a secondary metabolite produced by some saxicolous lichens. ZS was previously successfully encapsulated but never entrapped in mesoporous silica; instead, UA is, for the first time, encapsulated and in situ entrapped into the silica nanosystems in order to control the release over time. Both silica nanosystems have been characterized as far as their dimensions and superficial properties and loading capability. The antifouling activity was assessed against microorganisms from biopatinas colonising the Aurelian Walls in Rome. Our results have shown that the two nanosystems have complementary properties, thus it is possible to tune the antifouling efficiency by combining the two in different proportions.

Solid oxide photoelectrochemical cells (SOPECs) with inorganic ion-conducting electrolytes provide an alternative solution for light harvesting and conversion. Exploring potential photoelectrodes for SOPECs and understanding their operation mechanisms are crucial for continuously developing this technology. Here, ceria-based thin films were newly explored as photoelectrodes for SOPEC applications. It was found that the photoresponse of ceria-based thin films can be tuned both by Sm-doping-induced defects and by the heating temperature of SOPECs. The whole process was found to depend on the surface electrochemical redox reactions synergistically with the bulk photoelectric effect. Samarium doping level can selectively switch the open-circuit voltages polarity of SOPECs under illumination, thus shifting the potential of photoelectrodes and changing their photoresponse. The role of defect chemistry engineering in determining such a photoelectrochemical process was discussed. Transient absorption and X-ray photoemission spectroscopies, together with the state-of-the-art in operando X-ray absorption spectroscopy, allowed us to provide a compelling explanation of the experimentally observed switching behavior on the basis of the surface reactions and successive charge balance in the bulk.

A thermoresponsive Pluronic/alginate semisynthetic hydrogel is used to bioprint 3D hepatic constructs, with the aim to investigate liver-specific metabolic activity of the 3D constructs compared to traditional 2D adherent cultures. The bioprinting method relies on a bioinert hydrogel and is characterized by high-shape fidelity, mild depositing conditions and easily controllable gelation mechanism. Furthermore, the dissolution of the sacrificial Pluronic templating agent significantly ameliorates the diffusive properties of the printed hydrogel. The present findings demonstrate high viability and liver-specific metabolic activity, as assessed by synthesis of urea, albumin, and expression levels of the detoxifying CYP1A2 enzyme of cells embedded in the 3D hydrogel system. A markedly increased sensitivity to a well-known hepatotoxic drug (acetaminophen) is observed for cells in 3D constructs compared to 2D cultures. Therefore, the 3D model developed herein may represent an in vitro alternative to animal models for investigating drug-induced hepatotoxicity.

In the frame of the HERACLES (HEritage Resilience Against CLimate Events on Site) project, a set of cultural heritage sites was studied to improve their resilience against climate events. The mediaeval Town Walls of Gubbio, in the centre of Italy, are among these. Over the centuries, several factors including environmental actions and structural and material repairs have produced different criticalities, involving both structure and materials. A severe problem consists in the progressive degradation of the mortars binding the masonry. Since the wall body structure behaves/reacts properly only if the cohesion between mortar and stones is sufficiently large, it follows that mortars degradation represents a quite significant issue that deserves a special attention. The present work focuses on the characterization of the mortars sampled in various parts of the Walls, corresponding to different historical periods, restoration measures and interventions. They were characterized to determine the corresponding mineralogical and chemical compositions along with morphological features and to investigate their mechanical properties. For that purpose, penetrometric and sclerometric tests on site and ex situ laboratory techniques, such as X-ray diffraction, polarized light microscopy, scanning electron microscopy, thermogravimetry and differential thermal analysis, were used to examine the weathering effects on mortars and more generally their degradation state, in order to plan appropriate restoration and repair actions.