Synthesis Of Vanadium-based Oxides Nanostructures And Their Smart Properties

Based on the structural analysis of vanadium-based oxides, the responses to visible light, trace gas and temperature of their peculiar structure were detailedly investgated in this dissertation; meanwhile, the general synthetic routes have been developed to synthesize vanadium-based oxides nanostructures in order to improve their responsive properties. The details are summarized briefly as follows:(1) The multiresponsive function of monoclinic BiVO4 was first put forward and the monoclinic BiV04 nanoellipsoids with many exposed facets were designedly synthesized to improve their multiresponsive properties. As expected, these nanoellipsoids exhibited remarkably improved responses to visible-light, trace gas and temperature, showing potential applications as visible-light photocatalyst, gas sensor and temperature indicator to improve environmental quality and safety.(2) The authors first clarified the intermediate product as BiVO4·0.4H2O instead of tetragonal BiVO4 after carefully studying the formation process of monoclinic BiVO4 nanoellipsoids. This work not only shows prospective signs for studying possible formation mechanism of various monoclinic BiVO4 products but also provides an effective strategy to investigate the structural details of other hydrated compounds.(3) A novel assembly-fusion approach for fabricating monoclinic BiVO4 quantum tubes was first put forward. The ultranarrow diameter of 5 nm, ultrathin wall thickness down to 1 nm and exposed{020}facets endowed these quantum tubes with excellent dual-responses to visible light and temperature. This convenient and economic hydrothermal strategy is expected to be extended for preparing other inorganic quantum tubes, thereby holding promise for bringing on highly responsive properties.(4) The authors first realized the synthesis of V2O3 pseudocubes and then systematically investigated the effect of size and facets on the temperature-responsive metal-insulator transition in V2O3 system. The differences in surface energy and grain boundary connectivity accounted for their strong size and facet-dependent metal-insulator transition behavior. This work not only proposes a simple strategy for synthesizing high-quality nanocrystals but also provides an excellent platform to investigate the size and facet-dependent metal-insulator transition.