Tungsten suboxide W18O49 nanowhiskers are a material of great interest due to their potential high-end applications in electronics, near-infrared light shielding, catalysis, and gas sensing. The present study introduces three main approaches for the fundamental understanding of W18O49 nanowhisker growth and structure. First, W18O49 nanowhiskers were grown from γ-WO3/a-SiO2 nanofibers in situ in a scanning electron microscope (SEM) utilizing a specially designed microreactor (μReactor). It was found that irradiation by the electron beam slows the growth kinetics of the W18O49 nanowhisker, markedly. Following this, an in situ TEM study led to some new fundamental understanding of the growth mode of the crystal shear planes in the W18O49 nanowhisker and the formation of a domain (bundle) structure. High-resolution scanning transmission electron microscopy analysis of a cross-sectioned W18O49 nanowhisker revealed the well-documented pentagonal Magnéli columns and hexagonal channel characteristics for this phase. Furthermore, a highly crystalline and oriented domain structure and previously unreported mixed structural arrangement of tungsten oxide polyhedrons were analyzed. The tungsten oxide phases found in the cross section of the W18O49 nanowhisker were analyzed by nanodiffraction and electron energy loss spectroscopy (EELS), which were discussed and compared in light of theoretical calculations based on the density functional theory method. Finally, the knowledge gained from the in situ SEM and TEM experiments was valorized in developing a multigram synthesis of W18O49/a-SiO2 urchin-like nanofibers in a flow reactor.

CEITEC BUT Brno University of Technology Purkynova 123 CZ 61200 Brno Czech Republic

Department of Chemical Research Support Weizmann Institute of Science Rehovot 7610001 Israel

Department of Chemistry and Physics of Materials University of Salzburg Jakob Haringer Str 2A A 5020 Salzburg Austria

Department of Chemistry Faculty of Science Masaryk University Kotlarska 2 CZ 61137 Brno Czech Republic

Department of Materials Science Montanuniversität Leoben Franz Josef Straße 18 A 8700 Leoben Austria

Department of Molecular Chemistry and Materials Science Weizmann Institute of Science Rehovot 7610001 Israel

The Czech Academy of Sciences Institute of Scientific Instruments Kralovopolska 147 CZ 61264 Brno Czech Republic

Thermo Fisher Scientific Vlastimila Pecha 12 CZ 62700 Brno Czech Republic

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