Oxygen permeation from oxygen ion-conducting membranes coated with porous metals or mixed ionic and electronic conducting oxides

Increasing oxygen permeation from oxide membranes can enable the development of next-generation power generation technologies with high efficiency and reduced CO₂ mission. Here we introduce a new approach to design oxygen permeation membranes by covering the surfaces of pure oxygen-ion conductors with porous precious metal (Au and Ag) network or MIECs (LNO and LSCF). Oxygen permeation flux was enhanced by greatly by coating porous silver on the whole surface of pure oxygen ionconducting membranes such as Zr_0.85Y_0.16O_2-δ (YSZ), Bi _1.5Er_0.5O₃ (BE25), and La_0.8Sr _0.2Ga_0.8Mg_0.115Co_0.085O _3-δ (LSGMC). Oxygen permeation flux of La₂NiO _4+δ (LNO)-sputtered LSGMC membranes was comparable to silver-coated LSGMC membranes which demonstrates that membranes devoid of the use of noble metal can be prepared using this geometry. In contrast, oxygen permeation fluxes of YSZ and BE25 membrane did not increase by sputtering LNO or LSCF film because of the reaction between the membrane and LNO or LSCF. We obtained an oxygen permeation flux of 2.2 × 10^-8 cm ^-2 s^-1 at 700°C by coating porous silver on the feed side of LNO-sputtered LSGMC membrane, which was comparable to that of LNO membrane. The rate-limiting process for oxygen permeation through these membranes will be discussed.