Nanoconfined Lanthanum Hydride Nanoconfinement in Functionalized Carbon Hosts
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2024-11-22 |
| Journal | ECS Meeting Abstracts |
| Authors | Mohana Shivanna, Timoth Elmslie, Sakun Duwal, Catalin D. Spataru, Zak Piontkowski |
Abstract
Section titled āAbstractāMetal hydrides with a high hydrogen content have long been considered for materials-based hydrogen storage and but are now attracting attention as potential high-temperature superconductors. 1 Recently, we showed that cryo-milling lanthanum improves hydrogen diffusion, yielding a higher hydrogen-to-metal ratio of lanthanum hydride up to LaH 4 . 2 Another strategy for improving the thermodynamics and hydrogen desorption kinetics of metal hydrides is nanoconfinement within porous hosts. 3,4 However, this has not previously been achieved for lanthanum hydride (LaH x ) due to the difficulty of isolating nanoparticles of La or La-hydrides. In this work we demonstrate that LaH x can be infiltrated into two porous carbons: nitrogen-doped CMK-3 (NCMK-3) and undoped CMK-3, both with average pore size 4-5 nm. Transmission electron microscopy (TEM) images reveal that LaH x species are distributed uniformly throughout these hosts in NCMK-3 and CMK-3 with rod and spherical morphologies, respectively. X-ray absorption spectroscopy (XAS) and X-ray photoelectron microscopy (XPS) were used to probe the coordination environment of the LaH x species and composition lanthanum and nitrogen. Sieverts measurements indicate that LaH x @NCMK-3 desorbs up to 0.7 wt % hydrogen, which is higher than the non-nitrogen functionalized CMK-3 (0.5 wt%H). Density Functional Theory (DFT) and ab initio molecular dynamics (AIMD) calculations predict that host-guest interaction energies are favorable for porous carbon with pyridinic, pyrolic, or pyridonic nitrogen defects on a graphene surface, consistent with experimental data. Moreover, high-pressure experiments were conducted to understand the tunability of hydrogen content in presence of ammonia borane as a hydrogen source. These revealed that the as-prepared materials underwent an increase in H:La ratio from 1.5 to 3.0 with pressure. Our results demonstrate that nitrogen-doped nanoporous carbons can confine lanthanum hydrides, favor higher H:La ratios, and could serve as a platform for developing superconducting materials at relatively low pressures (compared with diamond anvil cells) and temperatures. -W. Guan, R. J. Helmley, V. Viswanathan Combining pressure and electrochemistry to synthesize superhydrides PNAS 2021 , 118 , e2110470118. Duwal, V. Stavila, C. Spataru, M. Shivanna, P. Allen, T. Elmslie, T. C. Seagle, J. Jeffries, N. Velisavljevic, J. Smith, P. Chow, Y. Xiao, Y. Meng, M. Somayazulu, P. A. Sharma Enhancement of hydrogen absorption and hypervalent metal hydride formation in lanthanum using cryogenic ball milling Phys. Rev. Mater. , 2024 , submitted. Stavila, S. Li, C. Dun, M. A. T. Marple, H. E. Mason, J. L. Snider, et al. Angew. Chem. Int. Ed. 2021, 60, 25815-25824. Schneemann, L. F. Wan, A. S. Lipton, Y.-S. Liu, J. L. Snider, A. A. Baker, et al. ACS Nano 2020, 14 , 10294-10304.