Dependence of hydrogen-absorption and -desorption characteristics on density of lithium–zirconium oxides exposed in air at room temperature

Abstract The dependence of the hydrogen (H)-absorption and -desorption characteristics of air-exposed Li2ZrO3 samples at room temperature on Li2ZrO3 densities of 2.53–3.78 g/cm3, related to the surface area, and the most stable trapping sites of H were investigated using weight gain measurement (WGM), elastic recoil detection (ERD), Fourier-transform infrared (FT-IR) spectroscopy, thermal desorption spectroscopy (TDS), gas chromatography (GC), and first-principles calculations. The WGM, ERD, and FT-IR spectra revealed that the H concentration in Li2ZrO3 increased with increasing air exposure time and relative humidity and decreasing density by splitting water (H2O). The TDS and GC analyses revealed that hydrogen molecules (H2), as well as H2O, were released from the air-exposed Li2ZrO3 at annealing temperatures less than 323 K. In addition, it was found by using a density functional theory (DFT) code that H atoms dissociated from H2O preferred to occupy oxygen (O) substitutional sites in Li2ZrO3.