Chalcogenide nanoclusters and their superstructures.

摘要

Oxide open-framework materials have been extensively studied in a variety of technological areas such as gas storage and separation, catalysis, sorption, and ion exchange. Due to their possibility to expand the traditional applications of open-framework materials into the fields of electrochemical sensors, photocatalysis, and optoelectronics, chalcogenide open-framework materials have attracted increasing attention since the first report in 1989. During past several years, several important systems of chalcogenide open-frameworks have been successfully developed in our group. In this dissertation, the synthetic strategies to access different classes of chalcogenide nanoclusters and control their assemblies into a variety of superstructures are described. Together with their syntheses and structures, interesting properties and potential applications of these chalcogenide materials are also discussed.; One of the most important structural features among the chalcogenide superstructures is that they are mainly based on three series of tetrahedral clusters: supertetrahedral cluster, penta-supertetrahedral clusters, and capped tetrahedral clusters. We have not only pushed the size limit of tetrahedral clusters up to 2nm but also synthesized the first tetrahedral cluster consisting of more than 100 core atoms. These large clusters are able to further function as building blocks for constructing different superstructures through corner-sharing chalcogen bridges or organic ligands. Three families of molecules (i.e., organic amines, inorganic cations, and metal complex molecules) have been successfully applied as templating agents to direct different systems of chalcogenide open-frameworks. Among the most significant synthetic achievements is the development of the thermally stable chalcogenide zeolite analogs from which microporosity was first generated. Equally important is the successful synthesis of pure inorganic chalcogenide open-frameworks exhibiting fast ionic conductivity at room temperature.; With the integration of both open structure and semiconductivity, interesting physical and chemical properties of chalcogenide open-framework materials were also explored. Optically, the chalcogenide open-frameworks exhibit tunable band gaps and photoluminescent emissions that depend on their compositions and structures. Electrically, inorganic chalcogenide open-frameworks exhibit fast ionic conductivity even at room temperature. Chalcogenide open-frameworks materials have also been demonstrated as efficient photocatalysts for water reduction with several advantages over dense semiconductors.