ABSTRACT
The discovery of low-dimensional metallic systems such as high-mobility metal oxide field-effect transistors, the cuprate superconductors, and conducting oxide interfaces (e.g., LaAlO3/SrTiO3) has stimulated research into the nature of electronic transport in two-dimensional systems given that the seminal theory for transport in disordered metals predicts that the metallic state cannot exist in two dimensions (2D). In this report, we demonstrate the existence of a metal-insulator transition (MIT) in highly disordered RuO2 nanoskins with carrier concentrations that are one-to-six orders of magnitude higher and with mobilities that are one-to-six orders of magnitude lower than those reported previously for 2D oxides. The presence of an MIT and the accompanying atypical electronic characteristics place this form of the oxide in a highly diffusive, strong disorder regime and establishes the existence of a metallic state in 2D that is analogous to the three-dimensional case.
ABSTRACT
When aluminosilicate zeolites, which are microporous crystalline scaffolds, intersect with electrochemistry, new opportunities arise for control of ion- and electron-transfer reactions. In this Account, we describe how zeolites modified with either redox solutes or nanocrystalline particles (which when electrified behave as nanoelectrodes) give rise to new reaction products for old catalytic schemes, improve catalytic turnovers relative to the zeolite-free electrocatalyst, and generate practical amounts of electrosynthesized product at nanoelectrode-modified zeolites. The electrochemical reactions driven at redox-modified zeolites demonstrate the ability of the truncated topography of the zeolite boundary to affect charge-transfer reactions.
Subject(s)
Zeolites/chemistry , Catalysis , ElectrochemistryABSTRACT
A review is given of past and potential analytical and other applications of electrodes overlayered with zeolites.
