title: Reversible phase modulation and hydrogen storage in multivalent VO2 epitaxial thin films.
abstract: Hydrogen, the smallest and the lightest atomic element, is reversibly incorporated into interstitial sites in vanadium dioxide (VO2), a correlated oxide with a 3d(1) electronic configuration, and induces electronic phase modulation. It is widely reported that low hydrogen concentrations stabilize the metallic phase, but the understanding of hydrogen in the high doping regime is limited. Here, we demonstrate that as many as two hydrogen atoms can be incorporated into each VO2 unit cell, and that hydrogen is reversibly absorbed into, and released from, VO2 without destroying its lattice framework. This hydrogenation process allows us to elucidate electronic phase modulation of vanadium oxyhydride, demonstrating two-step insulator (VO2)-metal (HxVO2)-insulator (HVO2) phase modulation during inter-integer d-band filling. Our finding suggests the possibility of reversible and dynamic control of topotactic phase modulation in VO2 and opens up the potential application in proton-based Mottronics and novel hydrogen storage.
authors.affiliation: Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea.
authors.forename: Hyojin
authors.initials: H
authors.lastname: Yoon
authors.affiliation: Materials Modeling and Characterization Department, Korea Institute of Materials Science (KIMS), Changwon 51508, Republic of Korea.|Department of Physics, Inha University, Incheon 22212, Republic of Korea.
authors.forename: Minseok
authors.initials: M
authors.lastname: Choi
authors.affiliation: Materials Modeling and Characterization Department, Korea Institute of Materials Science (KIMS), Changwon 51508, Republic of Korea.
authors.forename: Tae-Won
authors.initials: TW
authors.lastname: Lim
authors.affiliation: Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea.
authors.forename: Hyunah
authors.initials: H
authors.lastname: Kwon
authors.affiliation: Pohang Accelerator Laboratory, Pohang 37673, Republic of Korea.
authors.forename: Kyuwook
authors.initials: K
authors.lastname: Ihm
authors.affiliation: Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea.
authors.forename: Jong Kyu
authors.initials: JK
authors.lastname: Kim
authors.affiliation: Materials Modeling and Characterization Department, Korea Institute of Materials Science (KIMS), Changwon 51508, Republic of Korea.
authors.forename: Si-Young
authors.identifier: 0000-0003-1648-142X
authors.initials: SY
authors.lastname: Choi
authors.affiliation: Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea.
authors.forename: Junwoo
authors.initials: J
authors.lastname: Son