Electrochemical devices such as sensors, batteries have found widespread applications in energy, environment and biotechnology. The effective device performance is determined overwhelmingly by the electroactive materials comprising them.
Apart from chemical composition, charge transfer and diffusion related to various electrochemical phenomena have been observed to depend considerably on the spatial configuration and size of the electroactive components. The presentation will discuss the influence of (geometrical) confinement on redox processes and electron/ion transport via a few case studies. The examples that will be discussed during the presentation are as follows:
(a) Structure and electrochemical response of hemoglobin immobilized inside inorganic nanostructures and organic hosts[1, 2]: Using small angle synchrotron and neutron studies, confined protein resides in the non-aggregated state and is observed to display a more efficient reversible electrochemical response and higher thermal stability vis a vis proteins in solution.
(b) Ion transport in liquid electrolytes with functionalized oxide dispersants or “soggy sand” electrolytes[3, 4]: The dispersant surface chemical functionality and solvent parameters determines the character of the liquid-solid interface regime which determines the overall ion transport and mechanical properties of the electrolyte.
(c) Correlation of ion transport with solvent dynamics in polymer gels: Interesting changes occur with regard to solvation and (solvent) dynamics of low melting point solids such as plastic crystals entrapped within a polymer network. Various spectroscopic and scaling phenomena reveal enhanced charge carrier concentration and mobility of the ions in the confined liquid electrolyte compared to the free liquid electrolyte.
1. “Synchrotron small-angle x-ray scattering studies of hemoglobin nonaggregation confined inside polymer capsules”, Soumit S. Mandal, Satarupa Bhaduri, Heinz Amenitsch, and Aninda J. Bhattacharyya, J. Phys. Chem. B 2012, 116, 9604.
2. “Small angle neutron scattering studies of hemoglobin nonaggregation confined inside silica tubes”, Soumit S. Mandal, Peter Lindner, Viviana Cristiglio, and Aninda J. Bhattacharyya, 2013, under preparation.
3. “Ionic conductivity, mechanical strength and Li-ion battery performance of mono-functional and bi-functional (‘‘Janus’’) ‘‘soggy sand’’ electrolytes”, Shyamal K. Das, Soumit S. Mandal, Aninda J. Bhattacharyya, Energy Environ. Sc. 2011, 4, 1391
4. “Ion Transport in Liquid Salt Solutions with Oxide Dispersions: “Soggy Sand” Electrolytes”, Aninda J. Bhattacharyya, J. Phys. Chem. Lett, 2012, 3, 744 (Perspective and Cover Article).
5. “A crosslinked “polymer-gel” rechargeable lithium-ion battery electrolyte from free radical polymerization using nonionic plastic crystalline electrolyte medium”, Monalisa Patel, Aninda J. Bhattacharyya, Energy Environ. Sc. 2011, 4, 429
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