Abstract: The H2TRUST is a Coordination and Support Action by a team of European FCH industry leaders to foster a smooth and well managed transition to a full scale commercialization of FCH applications in Europe and, to aid the process by which all industry stakeholders are informed, prepared and confident from a safety perspective. Safety is considered in all hydrogen applications: production, storage, distribution, mobility, vehicles, non-vehicles and residential power generation.Here we will present the data collection from a set of hydrogen stakeholders, recognized experts in this field, consumers and incident response bodies associated with the fuel cells and hydrogen industries. These results will be disseminated by creating an online website with all the information collected. Best practices and methodology are going to be prepared in order to improve the hydrogen safety knowledge of the society.
Abstract: We present a millimeter scale reactor integrated PEM fuel cell energy source with an onboard hydrogen production reactor (realized by alkaline chemical hydride), and passive hydrogen buffering unit (realized by metal hydride) of hydrogen. A stacked system of reactor-hydrogen buffer-PEM fuel cell is demonstrated. The system is driven by the hydrolysis of the alkaline chemical hydride (NaOH+NaBH4) in the presence of micro porous catalyst layer (platinum catalyst (Ni-Pt)). The produced hydrogen gas from the reactor is buffered through the hydrogen buffer (Palladium metal hydride) and gets distributed (due to the pressure difference) onto the anode of the PEM fuel cell. The operational behaviour of the complete system is investigated with the hydrogen produced from the alkaline chemical hydride and pure hydrogen gas. Long term voltage measurements under a defined electrical load of the alkaline chemical hydride driven system was measured. The increase in time for the hydrogen production observed in the long term voltage measurement is anticipated to the degradation of the Ni-Pt catalyst. The system is “self-buffering” in nature so any change in electrical load can be handled during system operation.
Abstract: Na4Co3(PO4)2P2O7 is the unique crystal structure with multiple sodium-ion pathways in the structure. The electrochemical properties of Na4Co3(PO4)2P2O7 as a positive electrode for sodium-ion batteries were investigated. Na4Co3(PO4)2P2O7 had the multi redox couples in the highest potential region between 4.1 V and 4.7 V among ever reported sodium active materials and could deliver the reversible capacity of ca. 95 mAhg-1, corresponding to ca. 2.2 Na+. Na4Co3(PO4)2P2O7 also exhibited the high rate capabilities and had a small polarization in the charge - discharge profile even at the high current densities, resulting in high energy efficiency of the battery. These performances indicate Na4Co3(PO4)2P2O7 can be one of the good candidates for a positive electrode material of sodium-ion batteries.
Abstract: We present DFT investigations on the redox properties of quinone based precursors exhibiting growing interest from the electrochemists community due to their potential application as electrodes for new battery devices, with lower ecological footprint. A screening of various substituents is undertaken with the aim of providing guidelines to the experimentalists towards most promising candidates. A comparison of the effect of aromaticity extension is provided through the comparison of 1,4-benzo-/naphtho-/anthra-quinone and 9,10-anthraquinone backbones. Additionally, this work allowed the establishment of a ranking and quantitative assessment of substituents with respect to both increase and decrease of the redox voltage (useful for positive and negative electrodes, respectively) by considering such functionalizing groups for the monosubstitution of the 1,4-benzoquinone. Our computational work elucidates important fundamental relationships between redox voltage and local chemical bonding features, which may serve to the comprehension and design of new organic electrodes.
Abstract: Corn cob-like LiFePO4 (LFP) cathode material was simply synthesized through hydrothermal method using block copolymer (PEG-PPG-PEG) as the surfactant. The influence of pH value and reaction time on the morphology of LFP has been briefly investigated. The presence of copolymer plays an important role in the construction of the hierarchically microstructures. By adjusting the pH value and reaction time, platelet-like, hexagram-like, porous spindle-like and corn cob-like LFP microstructures were obtained. To gain the cell performance of the synthesized LFP, galvanostatic charging-discharging measurement on the as-prepared samples were performed. The porous spindle-like LFP/C shows unexpected electrochemical performance since the spindle-like LFP have large structure which prevents access for the liquid electrolyte. Corn cob-like LFP/C exhibits the best electrochemical performance, discharge specific capacities of 120 mAh g-1 after 100 cycles with capacity retention ratios of 80% at 0.1 C. This work also provides the possibility for further investigation into the shape-dependent electrochemical performance of other materials by optimizing the experimental parameters during hydrothermal synthesis.
Abstract: Using high resolution computed tomography (CT) the change of the morphometric parameters in depth of electrodes for lithium ion batteries with aging has been examined. Commercially available 2 Ah Li-ion cells were continuously cycled to different state of health (SOH). The cathodes were subsequently analyzed using CT with voxel size resolution of about 400 nm. For a quantitative analysis binarized images were evaluated and various properties such as the size distribution of active particles analyzed. Using this technique a decrease in the average particle size and an increase in number of particles of LiCoO2 with decreasing SOH of the battery is confirmed experimentally for the first time.
Abstract: Polymer grafting from graphitic carbon materials has been explored for several decades. Currently existing methods mostly employ harsh chemical treatment to generate defect site in graphitic carbon plane, which are used as active site for polymerization of precursors. Unfortunately, the treatment cause serious degradation of chemical structure and material properties. Here, we present a straightforward route for growth of polyaniline chain from nitrogen (N)-sites of carbon nanotubes. N site in the CNT wall initiates the polymerization of aniline monomer, which generates seamless hybrids composed of polyaniline directly grafted onto the CNT walls. The synthesized hybrids show excellent synergistic electrochemical performance, and are employed for electrodes of pseudo-capacitor. This approach offers an efficient way to obtain hybrid system consisting of conducting polymers directly grafted from graphitic dopant sites.
Abstract: Use of spark plasma sintering (SPS) allows improving thermoelectric figure of merit Z of bulk nanothermoelectrics but required parameters of SPS process for achievement of best Z can be defined only empirically. In the present study the finite elements method for investigation of electric and thermal processes which occur in volume and on boundaries of sintering particles is applied. As a geometrical model a structural cell of a sintered sample, containing contact “a truncated cone - a plate” has been chosen. Temperature distributions in the volume of a sample depending on amplitude, on-off time ratio and duration of impact of the electric current has been obtained for solid solution based on bismuth telluride using the energy balance equation and the equation of electric current continuity. Under certain conditions nonlinear and nonlocal processes start to arise. The calculated temperature distributions at different sintering conditions were comparing with empirically defined experimental parameters that lead to improved value of Z. The comparison allows formulating recommendations to achieve best conditions of SPS process for increase of Z. The present method can be used for management of SPS fabrication process for different application, not only for thermoelectrics.
Abstract: Regarding catalytic and plasmonic properties of gold nanoparticles (NPs), the novel area of research on photocatalytic gold properties has been recently started. In contrast with catalytically active gold NPs, where nanosized gold is recommended, our results showed that polydispersity of deposited gold NPs on semiconducting support was beneficial for photocatalytic activity under visible light irradiation. It is thought that wide size/shape distribution of gold NPs, and thus the ability of absorption of light in a wide wavelengths range is responsible for the high level of photoactivity. Though desirable absorption properties of plasmonic photocatalysts can be easily obtained by preparation of nanoparticles of different sizes and shapes, their photocatalytic activities under visible light irradiation are still low and should be enanced. The improvement of photocatalytic activities under visible light irradiation was achieved by enlargement of interfacial contact between titania and NPs of noble metals, extension of photoabsorption ranges (by preparation of NPs of various sizes and shapes or composed of two kinds of noble metals), and by deposition of noble metals NPs on faceted titania, i.e., octahedral (OAPs) and decahedral (DAPs). Plasmonic photocatalysts composed of titania and NPs of silver, gold or copper showed also high antiseptic properties under visible light irradiation, due to possible synergism of antiseptic properties of noble metals and photodisinfection properties of photocatalyst, since reactive oxygen species or photogenerated holes are formed on the surface of irradiated semiconductor.
Abstract: A co-catalyst was synthesized by photochemically depositing Pd nanoparticles onto TiO2 nanopowder support in a one-pot synthesis procedure. The Pd nanoparticles exhibited localised surface plasmon resonance observed using UV-VIS which increased the absorption cross-section of the co-catalyst system into the visible as well as UV regions of the spectrum. This was found to have a significant contribution to the photocatalytic activity of the catalyst in dye degradation experiments. The size, morphology and distribution of the Pd nanoparticles were determined by TEM, while the chemical state and amount of Pd deposited were analysed via XPS and ICP respectively.