a b s t r a c tSome compositions of ceramic hydrogen permeable membranes are promising for integration in high temperature processes such as steam methane reforming due to their high chemical stability in large chemical gradients and CO 2 containing atmospheres. In the present work, we investigate the hydrogen permeability of densely sintered ceramic composites (cercer) of two mixed ionic-electronic conductors: La 27 W 3.5 Mo 1.5 O 55.5 À δ (LWM) containing 30, 40 and 50 wt% La 0.87 Sr 0.13 CrO 3 À δ (LSC). Hydrogen permeation was characterized as a function of temperature, feed side hydrogen partial pressure (0.1-0.9 bar) with wet and dry sweep gas. In order to assess potentially limiting surface kinetics, measurements were also carried out after applying a catalytic Pt-coating to the feed and sweep side surfaces. The apparent hydrogen permeability, with contribution from both H 2 permeation and water splitting on the sweep side, was highest for LWM70-LSC30 with both wet and dry sweep gas. The Pt-coating further enhances the apparent H 2 permeability, particularly at lower temperatures. The apparent H 2 permeability at 700 1C in wet 50% H 2 was 1.1 Â 10 À 3 mL min À 1 cm À 1 with wet sweep gas, which is higher than for the pure LWM material. The present work demonstrates that designing dual-phase ceramic composites of mixed ionic-electronic conductors is a promising strategy for enhancing the ambipolar conductivity and gas permeability of dense ceramic membranes.

Planar metal-supported cell designs provide cost-effective scaling-up of solid oxide fuel cells and electrolyzers. Here, we report on the fabrication of a BaZr 0.85 Y 0.15 O 3-δ-NiO (BZY15-NiO) composite electrode and BaZr 0.85 Y 0.15 O 3-δ (BZY15) proton conducting electrolyte films on metal and ceramic substrates using pulsed laser deposition (PLD). The results demonstrate successful sequential deposition of porous electrode and dense electrolyte structure by PLD at moderate temperatures, without the need for subsequent high temperature sintering. The decrease in roughness of the metal substrate used for deposition by spray-coating intermediary oxide layers had significant importance to the fabrication of functional layers as thin films. Crystalline porous BZY15-NiO and dense BZY15 films were sequentially deposited at high substrate temperature on metal supports (MS) with or without an electron-conducting barrier oxide layer, e.g. MS/(BZY15-Ni)/(BZY15-NiO)/BZY15 and MS/CeO 2 /(BZY15-NiO)/BZY15. The different microstructures for electrode and electrolyte were achieved with deposition steps at different substrate temperatures (800, 600 °C) and a gradual decrease of the pressure of O 2 in the deposition chamber.

Metal supports for planar MS-PCEC were manufactured using tape-casting of low-cost ferritic stainless steel. A coating protecting the metal support against oxidation was applied by vacuum infiltration and a buffer layer of La 0.5 Sr 0.5 Ti 0.75 Ni 0.25 O 3-δ (LSTN) was further deposited to smoothen the surface. The BaZr 0.85 Y 0.15 O 3-δ -NiO (BZY15-NiO) cathode and the BaZr 0.85 Y 0.15 O 3-δ (BZY15) electrolyte were applied by pulsed laser deposition (PLD) at elevated substrate temperatures (at 700 °C and 600 °C respectively). The main challenges are related to the restrictions in sintering temperature and atmosphere induced by the metal support, as well as strict demands on the roughness of substrates used for PLD. Reduction treatment of the half cells confirmed that NiO in the BZY15-NiO layer was reduced to Ni, resulting in increased porosity of the BZY15-Ni cathode, while keeping the columnar and dense microstructure of the BZY15 electrolyte. Initial electrochemical testing with a Pt anode showed a total resistance of 40 •cm 2 at 600 °C. Through this work important advances in using metal supports and thin films in planar PCEC assemblies have been made.

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Metal supported cells are considered the next generation of Solid Oxide Fuel Cells due to higher robustness and cost-efficiency. However, improvement of the low temperature performance (< 700°C), increased durability and the use of manufacturing routes compatible to the metal substrate are key parameters for success. Coatings for porous metal supports in order to improve the oxidation resistance of the metal, reduce the chromium evaporation and poisoning, and increase the conductivity of the protective oxide scale, are developed. The oxidation of coated and non-coated substrates in air and wet hydrogen has been compared and shows that it is possible to increase the oxidation resistance at 600°C in air by more than 10 and wet hydrogen by more than 1000 by coating the pre-sintered porous metal substrate.