How the Environment Encourages the Natural Formation of Hydrated V₂O₅

Herein, we report the microscopic and spectroscopic signatures of the hydrated V₂O₅ phase, prepared from the α-V₂O₅ powder, which was kept in deionized water inside an airtight glass container for approximately 2.5 years. The experimental results show an evolution of the V⁴⁺ component in V 2p_3/2 core energy level spectra, and a peak corresponding to σ-OH^- bond appeared in the valence band spectra in the hydrated V₂O₅ powder sample due to the water intercalation. Vanadium metal oxide particles were found to be self-nucleated into micro/nanorods after a long period of exposure to an extremely humid environment. The distinct features in the spectra obtained with high-resolution transmission electron microscopy, micro-Raman scattering, and X-ray photoelectron spectroscopy confirmed the presence of structural water molecules for the first time in the long-aged naturally hydrated V₂O₅ phase.