| Abstract Scope |
Many 2-D oxides can be exfoliated and reassembled into high surface area solids, with applications in electrochemical charge storage and electrocatalysis, among others. The talk will begin with a review of the unique behavior of Mn ions in layered MnO2, and how Mn3+ point defects yield large improvements in electrochemical and catalytic properties. We then track, using in-operando structural methods, X-ray spectroscopy and Raman spectra, the nature of and effects of electrochemical strains that result from different geometries in free-standing random nanosheets vs. stacked nanosheets. Materials include single-layer and 1-, 2, and 3-layer perovskite-derived layers nanosheets. Highly ordered stacks of nanosheets show only interlayer strains while random assemblies show strains in the plane of the nanosheet (~1%) during charging. The cycling stability is notably better in random nanosheet floccules, which is linked to the strain relief mechanisms afforded by the nanosheet floccules and improved mass and electrical transport. |