Synthesis of Vanadium Oxide Nanofibers with Variable Crystallinity and V5+/V4+ Ratios

摘要

Tailoring the morphological, chemical, and physical properties of vanadium oxides (VOx) is crucial to optimize their performance in current and future applications. The present contribution proposes a new route to obtain VOx nanofibers with different V~(4+)/V~(5+) ratios and crystallinity. The method involves the exclusive electrospinning of water-free NH_(4)VO_(3)-saturated solutions including a reductant. Subsequent air-annealing under suitable conditions yields vanadium oxide fibers of 20–90 nm diameter and 10–50 m~(2)/g surface area. The presence of the reductant gives rise to VOx nanofibers with a considerable proportion of V~(4+). Then, the right choice of the calcination heating rate and temperature permits to modify the V~(4+)/V~(5+) ratio as well as the crystalline phase and crystallite size of the fibers. With the proposed methodology, long-range continuous single-phase orthorhombic V_(2)O_(5) and monoclinic V_(3)O_(7) nanofibers are obtained.