Whole-journey nanomaterial research in an electron microscope: from material synthesis, composition characterization,...

The whole-journey nanomaterial research from material synthesis, composition and structure characterizations, property measurements to device construction and tests in one equipment chamber provides a quick and unambiguous way of establishing the relationships between synthesis conditions, composition and structures, physical properties and nanodevice performances of nanomaterials; however, it still proves challenging. Herein, we report the whole-journey research of tungsten oxide nanowires in an environmental scanning electron microscope (ESEM) equipped with an x-ray energy dispersive spectrometer (EDS) and a multifunctional nanoprobe system. Tungsten oxide nanowires are synthesized by irradiating a tungsten filament using a high-energy laser in O₂ atmosphere with the dynamic growth processes of nanowires being directly visualized under ESEM observation. The as-synthesized nanowires are then characterized to be monoclinic W₁₈O₄₉ nanowires by combing in situ EDS and ex situ transmission electron microscopy. Important physical parameters, i.e. Young's modulus, breaking strength, and electrical conductivity, of W₁₈O₄₉ nanowires are determined based on in situ property measurements. Two-terminal electronic devices employing single W₁₈O₄₉ nanowires as the channel are in situ constructed and their performances as near-infrared photodetectors and water vapor sensors are studied. The whole-journey research establishes the relationships between synthesis conditions, composition and structures, physical properties and nanodevice performances of tungsten oxide nanowires, and can be applied to other nanomaterials.