Search

We fabricated monolithic solid state modules based on organometal CH3NH3PbI3 and CH3NH3PbI3-xClx perovskites using poly-(3-hexylthiophene) and Spiro-OMeTAD as hole transport materials (HTMs). In particular, we developed innovative and scalable patterning procedures to minimize the series resistance at the integrated series-interconnections. By using these optimization steps, we reached a maximum conversion efficiency of 8.2% under AM1.5G at 1 Sun illumination conditions using the CH3NH3PbI3-xClx perovskite and the poly-(3-hexylthiophene) as HTM. Finally, we investigated the double-step deposition of CH3NH3PbI3 using the Spiro-OMeTAD, reaching a maximum conversion efficiency on active area (10.08 cm2) equal to 13.0% (9.1% on aperture area) under AM1.5G at 1 Sun illumination conditions. This remarkable result represents the highest PCE value reached for the perovskite solar modules.

Iron phthalocyanine (FePc) was supported on carbon nanotubes (CNT) and black pearls (BP). The carbon supports were modified by a two-step treatment with nitric acid and ammonia gas to facilitate catalyst dispersion and obtain effective ORR active sites. The treatment allowed introducing oxygen and nitrogen functionalities on the carbon surface while maintaining an extensively developed porous structure, as demonstrated by elemental analysis and BET measurements. Electrochemical activity of the electrocatalysts was assessed by cyclic voltammetry and rotating disk voltammetry experiments. The catalyst obtained by supporting Fe on CNT modified with ammonia gas (Fe-CNT(NH 3 )) displayed the highest catalytic activity towards ORR at neutral pH as a results of the highest density of pyridinic nitrogen on the sample surface, as indicated by Xray photoelectron spectroscopy (XPS). The applicability of Fe-based electrocatalysts as ORR cathodes of microbial fuel cells (MFCs) was demonstrated by assembling single chamber air-cathodes MFCs and comparing the performance with that a MFC equipped with a reference Pt/C cathode.

Composite membranes made-up of sulphonated polyetheretherketone (SPEEK, DS = 0.5) and of a sulphonated and silylated hybrid organic–inorganic derivative of polyphenylsulphone (SiSPPSU, DS = 2) were prepared and characterised. The water and methanol uptake, as well as thermal properties, of blend membranes containing 5 and 10 wt.-% SiSPPSU were evaluated. The electrochemical performance of the membranes was evaluated by electrochemical impedance spectroscopy (EIS) and tested in a direct methanol fuel cell (DMFC) station. The presence of SiSPPSU modified the properties of SPEEK, allowing to increase its performance in terms of proton conductivity, thermal and hydrolytic stability. These blends appeared to be suitable electrolytes for DMFC applications.

Hybrid membranes based on highly sulfonated poly(ether ether ketone) (SPEEK, DS = 0.9) where titania network was dispersed by in situ sol–gel reactions were prepared and characterized. The syntheses were carried out using either a basic catalyst (pyridine) or a chelating agent (2,4-pentandione) to control the features of the inorganic network in the polymeric matrix. Membranes were characterized by thermogravimetric analysis (TG), field emission scanning electron microscopy (FE-SEM), and electrochemical impedance spectroscopy (EIS). The formation of the inorganic component did not introduce any porosity in the final material and both syntheses led to membranes with enhanced thermal stability, reduced water uptake and good proton conductivity ( σ = 5.8 × 10 −2 S cm −1 ) up to 120 °C, thus making the samples suitable for application as polymeric electrolytes at intermediate temperature.

Pulsed Laser Deposition technique was used to engineer heterostructures of Yttrium-stabilized Zirconia (YSZ) and Gadolinium-doped Ceria (GDC) on perovskite substrates like Neodymium Gallate (NGO) and Strontium Titanate (STO). Epitaxial superlattices of the same number of layers of both materials were deposited with each block thickness as thin as 2 unit cells up to 30 unit cells. X-ray diffraction (XRD) investigation of the (002) symmetrical reflection allowed to evaluate the amount of material deposited in each layer constituting the superlattices. (113) asymmetrical reflections were analyzed to investigate strain effects on YSZ and GDC lattice parameters, evidencing the cube on cube growth of these films.

dmfc

β-Al2TiO5 thin films were obtained by dip-coating silicon substrates in acid-catalyzed precursor sols of aluminum and titanium alkoxides with and without acetyl acetone as a chelating agent and sub...

Bilayer electrolytes made of barium cerate covered with a thin film of barium zirconate deposited by pulsed laser deposition show promise for improving chemical stability without greatly affecting electrochemical performance in fuel cell operation.

not Available.

The production of electric energy from solar radiation is nowadays one of the most investigated and developed “carbon free” technology. A throughout investigation of the ceramics most commonly used as heat transfer fluids and/or heat storage materials for concentrating solar power systems (i.e. alkaline and heart alkaline nitrate/nitrite mixtures) is here reported. The study stems by the need to base materials selection on an accurate and critical knowledge of all their characteristics, including their thermophysical, environmental compatibility, and economic features. At this purpose, a rating criterion have been established, to readily show the advantages and disadvantages of each material, and to highlight which characteristics of the examined materials need to be further investigated and improved. Nitrate/nitrite mixtures have also been compared with other ceramics used for thermal storage, such as solid fillers, liquid metals, other salt mixtures, or phase change materials.

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.

Chemical storage systems are a promising innovative route to overcome the issue of the solar irradiation storage, resulting as cost effective and with high energy density. A main problem with these kinds of materials is to design a synthesis method for preparing stable reactive structures, presenting at the same time a high volumetric charging/discharging enthalpy. At this purpose, a size controlled spinel was produced, characterized and investigated regarding its thermophysical and kinetics properties. The obtained powder presents an average diameter between 100 and 200 µm and an energy density of 133 J/g and an experimental test was carried out to verify the spinel morphology stability under thermal cycles. The specific heat is similar to other structured chemical storage system and makes the spinel feasible to be used also as sensible accumulation medium. Despite the relatively high particles size, and the expected small exposed reactive area, the charging, and especially discharging reaction rates resulted particularly favourable and comparable with the reported behaviour of micrometric powders. The particularly simple preparation method plus the cost effectiveness of the precursors leads to a quite convenient expected cost for the storage material, absolutely similar to commercially available accumulation systems.

When designing a concentrating solar power (CSP) system, selection of a proper heat transfer fluid (HTF) material is a key, especially when employed in parabolic trough CSP plants. In particular, the use of low melting mixtures as an alternative to the widely commonly used “solar salt” can increase the CSP manageably and, as a result, several innovative nitrite/nitrate mixtures have been proposed. However, very few thermodynamics data are available for these compounds, especially regarding ternary compositions. One of the most interesting low freezing mixture is prepared with sodium and potassium nitrate together with sodium nitrite. The aim of this work is to investigate the thermodynamics properties of this ternary system, starting from its binary subunits, studying the phase diagram of this compound both experimentally and by a regular solution model. At this purpose, the literature phase diagrams of the binary subsystem were simulated in order to obtain the fitting parameters necessary for the employed semi-predictive tool. Then, the ternary system was modeled and the results showed very good agreement with the experimental points. It is quite interesting to note that both the theoretical and experimental results showed a low melting zone presenting greater sodium nitrate molar fractions with respect to sodium nitrite than previously reported in literature. This would lead to a decrease in the HTF price and an improvement regarding the fluid toxicity.

Despite its large interesting as component for low melting HTF and HSM, very few thermodynamics information is available regarding calcium nitrate and its mixtures. In this paper the binaries between Ca(NO3)2 and both NaNO3 and KNO3 are experimentally investigate by DSC and Neutron scattering. The results show that the solid phase of the binaries is composed by a solid solution of single nitrates. The DSC pattern and the eutectic point were modeled by the regular solution theory and the fitting parameters are reported. © 2019 Author(s).

Enzymatic hydrolysis of poly(1,4-butylene 2,5-thiophenedicarboxylate) (PBTF) and poly(1,4-butylene 2,5-furandicarboxylate) (PBF) by Humicola insolens (HiC) and Thermobifida cellulosilytica (Cut) cutinases is investigated. For the first time, the different depolymerization mechanisms of PBTF (endo-wise scission) and PBF (exo-wise cleavage) has been unveiled and correlated to the chemical structure of the two polyesters. Keywords: Poly(1,4-butylene 2,5-thiophenedicarboxylate) (PBTF), Poly(1,4-butylene 2,5-furandicarboxylate) (PBF), Enzymatic hydrolysis, Endo/exo chain scission, Cutinases, Polyesters degradation

Dense micrometric La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM) films were deposited by spin-coating on porous LSGM scaffolds characterized by homogeneous pore structure. Porous anodes were infiltrated with aqueous nickel and nickel/copper nitrate solutions, dried and fired at 700 °C. Homogeneous metal coating with proper interconnection was observed by SEM, chemical stability confirmed by XRD, and electrical characterization of anodic substrates was performed. Catalytic activity of different anodes was evaluated ex-situ in a quartz micro-reactor fed with CH4:CO2 mixture at range 650 and 700 °C. To investigate the redox properties of the metallic phases, the anodic substrates were subjected to redox ageing cycles and characterized by H2-TPR.

Structure stability and electrical conductivity of La 1-x Sr x Fe 0.8 Cu 0.2 O 3-δ with x = 0.2, 0.4 were investigated both in air and in hydrogen to explore their potential applications as symmetric electrodes for solid oxide fuel cells. La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ (LSGM) electrolyte supported symmetric fuel cells were fabricated and tested in air/hydrogen ambient in 650–800 °C temperature range achieving a maximum power density of 162 mW cm −2 . To improve the cell performance, a composite electrode (70 wt% La 1-x Sr x Fe 0.8 Cu 0.2 O 3-δ −30 wt% Gd 0.2 Ce 0.8 O 3-δ ) was successfully evaluated both at the anode and the cathode sides decreasing the cell polarization resistance to 0.454 Ω cm 2 at 800 °C and reaching a single cell maximum power density of 294 mW cm −2 .

Perovskite solar cells employing CH3NH3PbI3-xClx active layers show power conversion efficiency (PCE) as high as 20% in single cells and 13% in large area modules. However, their operational stability has often been limited due to degradation of the CH3NH3PbI3-xClx active layer. Here, we report a perovskite solar module (PSM, best and av. PCE 10.5 and 8.1%), employing solution-grown TiO2 nanorods (NRs) as the electron transport layer, which showed an increase in performance (∼5%) even after shelf-life investigation for 2500 h. A crucial issue on the module fabrication was the patterning of the TiO2 NRs, which was solved by interfacial engineering during the growth process and using an optimized laser pulse for patterning. A shelf-life comparison with PSMs built on TiO2 nanoparticles (NPs, best and av. PCE 7.9 and 5.5%) of similar thickness and on a compact TiO2 layer (CL, best and av. PCE 5.8 and 4.9%) shows, in contrast to that observed for NR PSMs, that PCE in NPs and CL PSMs dropped by ∼50 and ∼90%, respectively. This is due to the fact that the CH3NH3PbI3-xClx active layer shows superior phase stability when incorporated in devices with TiO2 NR scaffolds. (Figure Presented).