| Abstract Scope |
In the case of exfoliated 2-D oxides, little work has been published concerning the thermal stability and phase transitions that occur upon heating these high surface area solids. The talk will describe the evolution of phases in layered oxides including MnO2 and CoO2 over broad temperature ranges, where porous assemblies of nanosheets yield porous monoliths of thermodynamically stable phases. We focus on measuring nucleation and growth of new phase fragments – to capture the mechanisms of structural phase transitions – using primarily Raman spectroscopy and X-ray total scattering. We demonstrate that it is feasible though not straightforward to track, for example, conversion of assemblies of MnO2 nanosheets into tunnel-structured MnO2. We further show that properties such as the electrochemical capacitance and electrocatalytic activity vary with the structure changes, giving confidence in our ability to track phase transitions from the very early stages of nucleation at the sub-nanometer size scale. |