Geopolymer/CeO(2) as Solid Electrolyte for IT-SOFC

As a material for application in the life sciences, a new composite material, geopolymer/CeO(2) (GP_CeO(2)), was synthesized as a potential low-cost solid electrolyte for application in solid oxide fuel cells operating in intermediate temperature (IT-SOFC). The new materials were obtained from alkali-activated metakaolin (calcined clay) in the presence of CeO(2) powders (x = 10%). Besides the commercial CeO(2) powder, as a source of ceria, two differently synthesized CeO(2) powders also were used: CeO(2) synthesized by modified glycine nitrate procedure (MGNP) and self-propagating reaction at room temperature (SPRT). The structural, morphological, and electrical properties of pure and GP_CeO(2)-type samples were investigated by X-ray powder diffraction (XRPD), Fourier transform infrared (FTIR), BET, differential thermal and thermogravimetric analysis (DTA/TGA), scanning electron microscopy (FE-SEM), energy dispersive spectrometer (EDS), and method complex impedance (EIS). XRPD and matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) analysis confirmed the formation of solid phase CeO(2). The BET, DTA/TGA, FE-SEM, and EDS results indicated that particles of CeO(2) were stabile interconnected and form a continuous conductive path, which was confirmed by the EIS method. The highest conductivity of 1.86 × 10(−2) Ω(−1) cm(−1) was obtained for the sample GP_CeO(2)_MGNP at 700 °C. The corresponding value of activation energy for conductivity was 0.26 eV in the temperature range 500–700 °C.