Nanostructured Ceramic Membranes for Hydrogen Isotope Processing

This work explores the use of interfacial hydrated layers in ionic conducting ceramic materials for tritiated water (HTO) adsorption and recovery. Low-temperature water adsorption properties of nanoscale structured ceramics combined with hydrogen isotope exchange in their hydrated layers may provide a low-cost and transformative avenue to address tritium management challenges. Two categories of materials were explored including i) simple oxides (TiO₂), ii) perovskite phases based on zirconates (BaZr_0.8Y_0.2O_3-δ (BZY20), BaCe_0.7Zr_0.1Y_0.1Yb_0.1O_3-δ (BCZYYb)). Nanostructured membranes were fabricated through multiple sintering methods to investigate the absorption, mobility, and isotope exchange effect. The increased conductivity of nanostructured TiO₂ membrane in the wet atmosphere and its polarization behavior confirm the existence of the proton conductivity in the nanoscale TiO₂membrane at low temperatures (&lt; 250○C). The difference of proton conductivity in H₂O and D₂O reveals the hopping mechanism of the proton conduction. In addition, the thermo-gravimetric analysis reveals strong water uptake below 250○C resulting in high proton conductivity at low temperatures. Control of interfacial proton conductivity was demonstrated by changing the grain size and porosity of the nanostructured membrane. Furthermore, in-situ Raman and electrical conductivity relaxation techniques were used to quantify isotope exchange rates as a function of temperature. Modeling and process level economic analysis was performed using extrapolation of data from H/D systems, and associated separation factors to understand the potential for tritium absorption and recovery.<br/><br/>References:<br/>J. Gao, Y. Meng, J. H. Duffy, K. S. Brinkman. “Low-Temperature Protonic Ceramic Fuel Cells through Interfacial Engineering of Nanocrystalline BaCe0.7Zr0.1Y0.1Yb0.1O3-δElectrolytes” Advanced Energy and Sustainability Research (2021):2100098<br/>J. Gao, Y. Meng, A. Benton, J. He, L.G. Jacobsohn, J. Tong, K.S. Brinkman. “Insights into the Proton Transport Mechanism in TiO2 Simple Oxides by In Situ Raman Spectroscopy.” ACS Applied Materials & Interfaces 12.34 (2020): 38012-38018.