Controlled synthesis of single-crystal VOx·nH2O nanoribbons via a hydrothermal reduction method

Abstract VO x · n H 2 O (2.0⩽ x ⩽2.5) nanoribbons have been synthesized by direct hydrothermal processing of the aqueous solution of NH 4 VO 3 and polyethylene glycol 400 (PEG-400) at pH 3.5–5.5. Techniques of XRD, SEM, TEM, HRTEM, ED, and XPS have been used to characterize the structure, morphology, and composition of the nanoribbons. The VO x · n H 2 O nanoribbons are up to ∼200 μm in length, 100–150 nm in width, 20–30 nm in thickness, and grow along the [010] direction. The ratios of V 4+ to V 5+ in the products can be readily controlled by carefully adjusting the periods of reaction time. PEG carries the roles of both transport and reducing agent. A coordination self-assembly mechanism was proposed to elucidate the formation of the VO x · n H 2 O nanoribbons.