| 1. |
- Masese, Titus, et al.
(författare)
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Honeycomb-Layered Oxides With Silver Atom Bilayers and Emergence of Non-Abelian SU(2) Interactions
- 2023
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Ingår i: Advanced Science. - : Wiley. - 2198-3844 .- 2198-3844. ; 10:6
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Tidskriftsartikel (refereegranskat)abstract
- Honeycomb-layered oxides with monovalent or divalent, monolayered cationic lattices generally exhibit myriad crystalline features encompassing rich electrochemistry, geometries, and disorders, which particularly places them as attractive material candidates for next-generation energy storage applications. Herein, global honeycomb-layered oxide compositions, Ag2M2TeO6 ((Formula presented.).) exhibiting (Formula presented.) atom bilayers with sub-valent states within Ag-rich crystalline domains of Ag6M2TeO6 and (Formula presented.) -deficient domains of (Formula presented.) ((Formula presented.)). The (Formula presented.) -rich material characterized by aberration-corrected transmission electron microscopy reveals local atomic structural disorders characterized by aperiodic stacking and incoherency in the bilayer arrangement of (Formula presented.) atoms. Meanwhile, the global material not only displays high ionic conductivity but also manifests oxygen-hole electrochemistry during silver-ion extraction. Within the (Formula presented.) -rich domains, the bilayered structure, argentophilic interactions therein and the expected (Formula presented.) sub-valent states ((Formula presented.), etc.) are theoretically understood via spontaneous symmetry breaking of SU(2)× U(1) gauge symmetry interactions amongst 3 degenerate mass-less chiral fermion states, justified by electron occupancy of silver (Formula presented.) and 5s orbitals on a bifurcated honeycomb lattice. This implies that bilayered frameworks have research applications that go beyond the confines of energy storage.
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| 2. |
- Masese, Titus, et al.
(författare)
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Mixed alkali-ion transport and storage in atomic-disordered honeycomb layered NaKNi 2 TeO 6
- 2021
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Honeycomb layered oxides constitute an emerging class of materials that show interesting physicochemical and electrochemical properties. However, the development of these materials is still limited. Here, we report the combined use of alkali atoms (Na and K) to produce a mixed-alkali honeycomb layered oxide material, namely, NaKNi2TeO6. Via transmission electron microscopy measurements, we reveal the local atomic structural disorders characterised by aperiodic stacking and incoherency in the alternating arrangement of Na and K atoms. We also investigate the possibility of mixed electrochemical transport and storage of Na+ and K+ ions in NaKNi2TeO6. In particular, we report an average discharge cell voltage of about 4 V and a specific capacity of around 80 mAh g–1 at low specific currents (i.e., < 10 mA g–1) when a NaKNi2TeO6-based positive electrode is combined with a room-temperature NaK liquid alloy negative electrode using an ionic liquid-based electrolyte solution. These results represent a step towards the use of tailored cathode active materials for “dendrite-free” electrochemical energy storage systems exploiting room-temperature liquid alkali metal alloy materials.
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| 3. |
- Kanyolo, Godwill Mbiti, et al.
(författare)
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Honeycomb layered oxides: Structure, energy storage, transport, topology and relevant insights
- 2021
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Ingår i: Chemical Society Reviews. - : Royal Society of Chemistry (RSC). - 1460-4744 .- 0306-0012. ; 50:6, s. 3990-4030
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Forskningsöversikt (refereegranskat)abstract
- The advent of nanotechnology has hurtled the discovery and development of nanostructured materials with stellar chemical and physical functionalities in a bid to address issues in energy, environment, telecommunications and healthcare. In this quest, a class of two-dimensional layered materials consisting of alkali or coinage metal atoms sandwiched between slabs exclusively made of transition metal and chalcogen (or pnictogen) atoms arranged in a honeycomb fashion have emerged as materials exhibiting fascinatingly rich crystal chemistry, high-voltage electrochemistry, fast cation diffusion besides playing host to varied exotic electromagnetic and topological phenomena. Currently, with a niche application in energy storage as high-voltage materials, this class of honeycomb layered oxides serves as ideal pedagogical exemplars of the innumerable capabilities of nanomaterials drawing immense interest in multiple fields ranging from materials science, solid-state chemistry, electrochemistry and condensed matter physics. In this review, we delineate the relevant chemistry and physics of honeycomb layered oxides, and discuss their functionalities for tunable electrochemistry, superfast ionic conduction, electromagnetism and topology. Moreover, we elucidate the unexplored albeit vastly promising crystal chemistry space whilst outlining effective ways to identify regions within this compositional space, particularly where interesting electromagnetic and topological properties could be lurking within the aforementioned alkali and coinage-metal honeycomb layered oxide structures. We conclude by pointing towards possible future research directions, particularly the prospective realisation of Kitaev-Heisenberg-Dzyaloshinskii-Moriya interactions with single crystals and Floquet theory in closely-related honeycomb layered oxide materials. This journal is
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| 4. |
- Masese, Titus, et al.
(författare)
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Unveiling structural disorders in honeycomb layered oxide: Na2Ni2TeO6
- 2021
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Ingår i: Materialia. - : Elsevier BV. - 2589-1529. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Honeycomb layered oxides have garnered tremendous research interest in a wide swath of disciplines owing not only to the myriad physicochemical properties they exhibit, but also their rich crystal structural versatility. Herein, a comprehensive crystallographic study of a sodium-based Na2Ni2TeO6 honeycomb layered oxide has been performed using atomic-resolution transmission electron microscopy, elucidating a plethora of atomic arrangement (stacking) disorders in the pristine material. Stacking disorders in the arrangement of honeycomb metal slab layers (stacking faults) occur predominantly perpendicular to the slabs with long-range coherence length and enlisting edge dislocations in some domains. Moreover, the periodic arrangement of the distribution of alkali atoms is altered by the occurrence of stacking faults. The multitude of disorders innate in Na2Ni2TeO6 envisage broad implications in the functionalities of related honeycomb layered oxide materials and hold promise in bolstering renewed interest in their material science. Correction published, see: https://doi.org/10.1016/j.mtla.2021.101104
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