A new route to single crystalline vanadium dioxide nanoflakes via thermal reduction

Large-area single-crystalline vanadium dioxide nanoflakes were first fabricated via a thermal reduction method in a tube furnace. The sample was characterized by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The results show that VO₂ nanoflakes are single-crystalline with a monoclinic structure. The VO₂ nanoflakes have a width of 200–300 nm, a thickness of 50–100 nm, and a length up to 1–2 μm. It is found that single-crystalline VO₂ nanoflakes show a novel and complicated 5–7-step Li-storage behavior for an insertion amount of <0.6 mol lithium per mol of VO₂.