Self-assembled Nanocomposite:Synthesis And Application In Electrocatalysis And Smart Response

The goal of this dissertation is to explore the controllable synthesis of functional self-assembled nanocomposite by the understanding of the structural characteristics of reaction component as well as the target products, providing the effective methodology to control both the nanostructure and morphology of the final products. Moreover, by clearly understanding the morphology and structural characteristics of the final product, the corresponding structure-dependent properties of the as-obtained functional self-assembled nanocomposite, especially for the electrocatalysis and intelligent energy-saving areas were also investigated in this dissertation. The details are summarized briefly as follows:(1) We demonstrate a very efficient and stable water-oxidation nanocomposite catalyst as the oxygen-evolving anode in that mesoporous carbon nitride scaffold with inbuilt functionalities are applied to rivet [Co4(H2O)2(PW9O34)2]10-clusters. Here the abundant-metal-based polyoxometalate complex [Co4(H2O)2(PW9O34)2]10-is a hydrolytically and oxidatively stable, homogeneous, and efficient molecular catalyst for the oxidation of water. Mesoporous carbon nitride is used as an immobilization matrix to improve the catalytic water oxidation activity, structural durability and cyclability of the assembled nanostructures. Our results suggest that the nanoscale assembly of functional components provides a promising route to significantly improve the electrocatalytic water-splitting systems. The direct evidence of the interaction between the functional components was provided to explain the highly active catalytic mechanism.(2) We develop a hybrid consisting of Co3O4nanocrystals supported on single-walled carbon nanotubes (SWNTs) via a simple self-assembly approach. The resulting Co3O4/SWNTS hybrid as a highly catalytic activity electrode for the OER exhibits much enhanced catalytic activity as well as superior stability under neutral and alkaline conditions, while the bare Co3O4only performs well in alkaline solutions. Moreover, the turnover frequency for the OER exhibited by Co3O4/SWNTs in neutral water shows more advantages than bare Co3O4catalysts. Synergetic chemical coupling effects between Co3O4nanocrystals and SWNTs, revealing by the synchrotron XANES technique, are regarded to contribute the activity, cycling stability and stable operation under neutral condition. The SWNTs is used as an immobilization matrix to substantially increase in the active electrode surface area, enhance the durability of catalyst under neutral conditions and improve electronic coupling between Co redox-active sites of Co3O4and the electrode surface.(3) We design a novel thermoresponsive fluorescent nanocomposite, which are synthesized by coating the indium tin oxide nanocrystals (ITO) with an amphiphilic copolymer consisting of poly(maleic anhydride-alt-l-octadecene) and poly(N-isopropylacrylamide) via a simple self-assembly method. The nanocomposite exhibits reversible temperature dependent on-off fluorescence properties in solution within mild temperature range. In addition, the nanocomposite exhibits a sharp, reversible, clear-opaque transition in solution, which is controlled by temperature or near infrared light. Thus, thermosensitive ITO@PNIPAM nanocomposite may have potential use for biosensor and stimuli-responsive smart systems applications.(4) We successfully demonstrate a novel self-rolling nanocomposite thin film, which are synthesized by depositing the ITO nanocrystals@copolymer on polycaprolactone (PCL) substrates by self-assembly method. The nanocomposite thin film exhibits thermoresponsive self-rolling behaviour within mild temperature range and reversible thermochromic properties in visible and near-infrared regions. Moreover, infrared light can also control self rolling behaviour of the thin film, in which the ITO nanocrystals acted as a nano-heater to raise the local temperature of the thin film via the photothermal conversion of the ITO nanocrystals. Our resluts suggest that the nanocomposite thin film provides a promising intelligent windows to control solar heat entering the built environment in saving energy fields.