Cationic groups in polystyrene/O-PBI blends influence performance and hydrogen crossover in AEMWE.

This study examines the effect of various quaternary ammonium groups on AEMWE performance and hydrogen crossover in blends of quaternized polystyrenes with O-PBI. Due to their higher hydroxide conductivity (69 mS cm at 80 °C, 90% RH), trimethylammonium groups enable AEMWE to reach 1.0 A cm at 2.

Experimental Requirements for High-Temperature Solid-State Electrochemical TEM Experiments.

The ability to perform both electrochemical and structural/elemental characterization in the same experiment and at the nanoscale allows to directly link electrochemical performance to the material properties and their evolution over time and operating conditions. Such experiments can be important for the further development of solid oxide cells, solid-state batteries, thermal electrical devices, and other solid-state electrochemical devices. The experimental requirements for conducting solid-state electrochemical TEM experiments in general, including sample preparation, electrochemical measurements, failure factors, and possibilities for optimization, are presented and discussed.

Ion-beam deposited platinum as electrical contacting material in operando electron microscopy experiments at elevated temperatures.

Establishing a stable and well conducting contacting material is critical for operando electron microscopy experiments of electrical and electrochemical devices at elevated temperatures. In this contribution, the nanostructure and electrical conductivity of ion beam deposited Pt are investigated both in vacuum and in oxygen as a function of temperature. Its microstructure is relatively stable up to a temperature of approx.

Electrochemical Impedance Spectroscopy Integrated with Environmental Transmission Electron Microscopy.

The concept of combining electrical impedance spectroscopy (EIS) with environmental transmission electron microscopy (ETEM) is demonstrated by testing a specially designed micro gadolinia-doped ceria (CGO) sample in reactive gasses (O and H /H O), at elevated temperatures (room temperature-800 °C) and with applied electrical potentials. The EIS-TEM method provides structural and compositional information with direct correlation to the electrochemical performance. It is demonstrated that reliable EIS measurements can be achieved in the TEM for a sample with nanoscale dimensions.

Unravelling the role of dopants in the electrocatalytic activity of ceria towards CO reduction in solid oxide electrolysis cells.

CO reduction in Solid Oxide Electrolysis Cells (SOECs) is a key-technology for the transition to a sustainable energy infrastructure and chemical industry. Ceria (CeO) holds great promise in developing highly efficient, cost-effective and durable fuel electrodes, due to its promising electrocatalytic properties, and proven ability to suppress carbon deposition and to tolerate high concentrations of impurities. In the present work, we investigate the intrinsic electrocatalytic activity of ceria towards CO reduction by means of electrochemical impedance spectroscopy (EIS) on model systems with well-defined geometry, composition and surface area.

Kinetics of CO/CO2 and H2/H2O reactions at Ni-based and ceria-based solid-oxide-cell electrodes.

The solid oxide electrochemical cell (SOC) is an energy conversion technology that can be operated reversibly, to efficiently convert chemical fuels to electricity (fuel cell mode) as well as to store electricity as chemical fuels (electrolysis mode). The SOC fuel-electrode carries out the electrochemical reactions CO2 + 2e(-) ↔ CO + O(2-) and H2O + 2e(-) ↔ H2 + O(2-), for which the electrocatalytic activities of different electrodes differ considerably. The relative activities in CO/CO2 and H2/H2O and the nature of the differences are not well studied, even for the most common fuel-electrode material, a composite of nickel and yttria/scandia stabilized zirconia (Ni-SZ).

TOF-SIMS characterization of impurity enrichment and redistribution in solid oxide electrolysis cells during operation.

TOF-SIMS analyses of state-of-the-art high temperature solid oxide electrolysis cells before and after testing under different operating conditions were performed. The investigated cells consist of an yttria stabilized zirconia (YSZ) electrolyte, a La1-xSrxMnO3-δ composite anode and a Ni-YSZ cermet cathode. The surfaces and cross-sections of the cells were analyzed, and several elemental impurities like Si, Ca and Na were identified and spatially mapped and their enrichment and migration during operation is reported.

Defining chemical expansion: the choice of units for the stoichiometric expansion coefficient.

Chemical expansion refers to the spatial dilation of a material that occurs upon changes in its composition. When this dilation is caused by a gradual, iso-structural increase in the lattice parameter with composition, it is related to the composition change by the stoichiometric expansion coefficient. In this work, three different approaches to defining the stoichiometric expansion coefficient (αS) are discussed.

Experimental determination of the Onsager coefficients of transport for Ce(0.8)Pr(0.2)O(2-delta).

For a mixed oxide-ion and electron conducting oxide, with oxygen vacancies (V(O)) and electrons (e') or holes (h ) as charge carriers, a flux of (V(O)) (J(i)) can in principle be driven, not only directly by its own electrochemical potential gradient (inverted Delta eta(i)), but also indirectly by that of electrons (inverted Delta eta(e)), and vice versa for the flux of electrons (J(e)). It is common practice to assume that electrons and mobile ions migrate independently, despite the lack of experimental evidence in support of this. Here, all the Onsager coefficients, including the cross coefficients, have been measured for Ce(0.