Alessandra D'Epifanio

Solid-state solar modules based on mesoscopic organometal halide perovskite: a route towards the up-scaling process

We fabricated the first solid state modules based on organometal halide perovskite CH3NH3PbI3-xClx using Spiro-OMeTAD and poly(3-hexylthiophene) as hole transport materials. Device up-scaling was performed using innovative procedures to realize large-area cells and the integrated series-interconnections. The perovskite-based modules show a maximum conversion efficiency of 5.1% using both poly(3-hexylthiophene) and Spiro-OMeTAD. A long-term stability test was performed (in air, under AM1.5G, 1 Sun illumination conditions) using both materials showing different behaviour under continuous light stress. Whilst the poly(3-hexylthiophene)-based module efficiency drops by about 80% with respect to the initial value after 170 hours, the Spiro-based module shows a promising long-term stability maintaining more than 60% of its initial efficiency after 335 hours.

Design and fabrication of a chemically-stable proton conductor bilayer electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs)

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.

Nano-structured perovskite oxide electrodes for planar electrochemical sensors using tape casted YSZ layers

Solid-state NO 2 sensors based on yttria stabilized zirconia (YSZ), an O 2- conductor, combined either with an n- (WO 3 ), or a p-type semiconducting oxide (LaFeO 3 ), or a mixed electronic and ionic conductor (La 0.8 Sr 0.2 FeO 3 ) were investigated. Platinum parallel finger electrodes were applied on the surface of tape-casted YSZ layers and attached with gold wires for current collection. Nanocrystalline perovskite powders were prepared using different chemical methods: LaFeO 3 by the thermal decomposition of the LaFe-hexacyanide complex, and La 0.8 Sr 0.2 FeO 3 by a sol-gel route. A sub-micrometric commercial WO 3 powder was used. The oxide powders were mixed with a screen-printing oil and deposited on one Pt finger electrode. The presence of the oxide powder makes one of the electrodes different from the other in terms of catalytic activity, specific surface area, gas adsorption and reaction kinetics. Both electrodes were wholly exposed to the same gas atmosphere, without using reference air. The sensors were investigated at fixed temperature (450-700 °C) by measuring the electromotive force (EMF) at different concentrations of NO 2 and CO in air in the range 20-1000 ppm. A fast and stable response was measured for all the tested sensors. An EMF of opposite sign was measured for p- and n-type semiconducting based sensors upon exposure to the same gas. After increasing the grain size of the nano-structured La 0.8 Sr 0.2 FeO 3 powder by a heat treatment at 900 °C for 4 h, the response to NO x became small, slow and unstable.

Thermal, electrochemical and structural properties of stabilized LiNiyCo1−y−zMzO2 lithium-ion cathode material prepared by a chemical route

Layered compounds, such as LiNiO2 and LiCoO2 , have been extensively studied as active cathodic materials in lithium-ion batteries. Mixed oxides having general formula LiNiyCo1−yO2 represent a good compromise between the limited cyclability of LiNiO2 and the high cost of LiCoO2. However, recent studies have demonstrated that LiNiyCo1−yO2 compounds are thermally unstable in their charged state, undergoing exothermic reactions that might cause thermal runaway and safety concern. The stability of the compounds may be greatly controlled by doping with a suitable metal, M = Al, Mg. In this work we further investigate the role of the doping metal on the thermal, electrochemical and structural characteristics of the LiNiyCo1−y−zMzO2 electrode materials. These materials were prepared using a soft chemistry route, to achieve the proper control of the chemical homogeneity and of the microstructural properties of the final samples. The thermal behavior of the doped LiNiyCo1−y−zMzO2, where M = Al, was studied using differential scanning calorimetry. The structural properties upon cycling were investigated by a recently, in-house developed, in situ energy dispersive X-ray diffraction (EDXD) technique. The reversibility and rate capabilities of the cathodes in lithium cells were characterized using electrochemical equipment.

PEO based polymer electrolyte lithium-ion battery

Abstract Nanocomposite ZrO 2 -added PEO-based solid polymer electrolytes and nanocomposite Ag-added LiFePO 4 cathodes have been utilized to realize all solid state metallic lithium batteries. In this work the electrochemical properties of these materials will be illustrated and discussed.

A novel single chamber solid oxide fuel cell based on chemically stable thin films of Y-doped BaZrO3 proton conducting electrolyte

A novel single chamber solid oxide fuel cell operating at 550 °C was fabricated depositing a fully-dense, 650 nm thick, BaZr0.8Y0.2O3−δ (BZY) films on Ni-BZY anodes by pulsed laser deposition. Using an optimized cathode for proton conductor electrolytes, an open circuit voltage of 0.53 V and a power density output of 36 mW cm−2 were reached in the single chamber operation mode.

Design of iron(II) pthalocyanine (FePc) derived oxygen reduction electrocatalysts for high power density microbial fuel cells

Abstract Iron(II) phthalocyanine (FePc) deposited onto two different carbonaceous supports was synthesized through an unconventional pyrolysis‐free method. The obtained materials were studied in the oxygen reduction reaction (ORR) in neutral media through incorporation in an air‐breathing cathode structure and tested in an operating microbial fuel cell (MFC) configuration. Rotating ring disk electrode (RRDE) analysis revealed high performances of the Fe‐based catalysts compared with that of activated carbon (AC). The FePc supported on Black‐Pearl carbon black [Fe‐BP(N)] exhibits the highest performance in terms of its more positive onset potential, positive shift of the half‐wave potential, and higher limiting current as well as the highest power density in the operating MFC of (243±7) μW cm−2, which was 33 % higher than that of FePc supported on nitrogen‐doped carbon nanotubes (Fe‐CNT(N); 182±5 μW cm−2). The power density generated by Fe‐BP(N) was 92 % higher than that of the MFC utilizing AC; therefore, the utilization of platinum group metal‐free catalysts can boost the performances of MFCs significantly.

Nafion/Tin Oxide Composite Membranes for Direct Methanol Fuel Cells

Composite Nafion-based membranes were prepared and characterized, using hydrated tin oxide as a filler. Water Uptake and proton conductivity were measured as a function of temperature. Methanol crossover through reference Nafion and composite membranes was evaluated by a voltametric method and the electrochemical performance of the membranes was assessed by tests in a single direct methanol fuel cell (DMFC). The formation of the composite improved the properties of Nafion matrix in terms of methanol crossover and DMFC performance, allowing to identify Nafion membrane with 10wt% tin oxide as a suitable electrolyte to be used in a DMFC device operating at T ≥ 90°C. ©The Electrochemical Society.

Composite polymer electrolytes for fuel cell applications: filler-induced effect on water sorption and transport properties.

Nafion- and sulfonated polysulfone (SPS)- based composite membranes were prepared by incorporation of SnO2 nanoparticles in a wide range of loading (0

Poly(phenylene sulfide sulfone) based membranes with improved stability for vanadium redox flow batteries

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