Use of interplay between A-site non-stoichiometry and hydroxide doping to deliver novel proton-conducting perovskite oxides
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The magnitude of ionic conductivity is known to depend upon both mobility and number of available carriers. For proton conductors, hydration is a key factor in determining the charge–carrier concentration in ABO3 perovskite oxides. Despite the high reported proton mobility of calcium titanate (CaTiO3), this titanate perovskite has thus far been regarded as a poor proton conductor due to the low hydration capability. Here, the enhanced proton conductivity of the defective calcium titanate Ca0.92TiO2.84(OH)0.16 prepared by replacing lattice oxygens with hydroxyl groups via a solvothermal route is shown. Conductivity measurements in a humidified Ar atmosphere reveal that, remarkably, this material exhibits one order of magnitude higher bulk conductivity (10−4 Scm−1 at 200 °C) than hydrated stoichiometric CaTiO3 prepared by traditional solid-state synthesis due to the higher concentration of protonic defects and variation in the crystal structure. The replacement of Ca2+ by Ni2+ in the Ca1−xTi1O3−2x(OH)2x, which mostly exsolve metallic Ni nanoparticles along orthorhombic (100) planes upon reduction, is also demonstrated. These results suggest a new strategy by tailoring the defect chemistry via hydration or cation doping followed by exsolution for targeted energy applications.
Lee , J , Naden , A B , Savaniu , C D , Connor , P A , Payne , J L , Skelton , J , Gibbs , A , Hui , J , Parker , S & Irvine , J T S 2021 , ' Use of interplay between A-site non-stoichiometry and hydroxide doping to deliver novel proton-conducting perovskite oxides ' , Advanced Energy Materials , vol. 11 , no. 37 , 2101337 . https://doi.org/10.1002/aenm.202101337
Advanced Energy Materials
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