Novel Proton-Conducting Nanocomposites for Hydrogen Separation Membranes
21 International Conference on Solid State Ionics
18-23 Jun 2017
conference_type.international conference, Padua
|| Sadykov Vladislav Aleksandrovich
, Bespalko Yulia Nikolaevna
, Krasnov Aleksey
, Skriabin Pavel Ivanovich
, Sadovskaya Ekaterina Mikhajlovna
, Eremeev Nikita Fedorovich
, Krieger Tamara Andreevna
, Belyaev Vladimir Dmitrievich
, Vinokurov Zakhar
, Uvarov Nikolai Favstovich
, Ulikhin Artem Sergeevich
Boreskov Institute of Catalysis SB RAS
Novosibirsk State University
Novosibirsk State Technical University
Institute of Solid State Chemistry and Mechanochemistry SB RAS
Budker Institute of Nuclear Physics SB RAS
Design of oxide and nanocomposite materials with high mixed protonic-electronic conductivity such as lanthanide niobates and tungstates  is encouraging approach in developing hydrogen separation membranes. This work aims at elucidating the relations between the composition, structure, oxygen and protonic mobility of such materials.
La0.99Ca0.01NbO4, LaNb3O9 and Nd5.5(Mo,W)O11.25 σ were synthesized by Pechini route . Nanocomposites of tungstates with LaNb3O9 and Ni+Cu were prepared by US dispersion or mechanical treatment in a high energy mill, then sintered using conventional thermal sintering and hot pressing. All obtained materials were characterized using XRD, TEM with EDX analysis, IR and Raman spectroscopy. For powdered samples the oxygen and protonic mobility were studied by isotope exchange with CO182 and D2O, respectively. For sintered pellets the unit cell volume and weight relaxation techniques were applied to estimate the oxygen and water chemical diffusion coefficients. The protonic conductivity was studied by Van der Pauw technique.
The main phases were scheelite for La0.99Ca0.01NbO4, perovskite for LaNb3O9 and fluorite for Nd5.5(Mo,W)O11.25 σ. Extended bulk/surface defects were observed by TEM agreeing with IR and Raman spectroscopy data. The oxygen mobility studies revealed two routes of bulk oxygen diffusion related to two phases in nanocomposites. . H2O desorption experiments revealed the working temperature range being 300 – 450 °C. The protonic conductivity values (~ 10 4 Ω 1cm 1 at 400 °C) agree with the literature data  and are enough high for practical application. Proton tracer and chemical diffusion coefficients values are ~10 11 and ~10 5 cm2/s at working temperatures respectively.
The work was supported by the Russian Science Foundation (Project 16-13-00112).
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