Nanostructured hydrated vanadium oxides (V2O5·nH2O) are actively being researched for applications in energy storage, catalysis, and gas sensors. Recently, a one-step exfoliation technique for fabricating V2O5·nH2O nanosheets in aqueous media was reported; however, the underlying mechanism of exfoliation has been challenging to study. Herein, we followed the synthesis of V2O5·nH2O nanosheets from the V2O5 and VO2 precursors in real time using solution- and solid-state 51V NMR. Solution-state 51V NMR showed that the aqueous solution contained mostly the decavanadate anion [H2V10O28]4- and the hydrated dioxovanadate cation [VO2·4H2O]+, and during the exfoliation process, decavanadate was formed, while the amount of [VO2·4H2O]+ remained constant. The conversion of the solid precursor V2O5, which was monitored with solid-state 51V NMR, was initiated when VO2 was in its monoclinic forms. The dried V2O5·nH2O nanosheets were weakly paramagnetic because of a minor content of isolated V4+. Its solid-state 51V signal was less than 20% of V2O5 and arose from diamagnetic V4+ or V5+.This study demonstrates the use of real-time NMR techniques as a powerful analysis tool for the exfoliation of bulk materials into nanosheets. A deeper understanding of this process will pave the way to tailor these important materials.

中文翻译：

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使用实时51V NMR深入了解V2O5·nH2O纳米片形成的剥落过程。

纳米结构化水合氧化钒（V2O5·nH2O）正在积极研究，用于储能，催化和气体传感器。最近，报道了一种在水性介质中制备V2O5·nH2O纳米片的一步剥离技术。然而，去角质的潜在机制一直很难研究。在这里，我们跟踪了使用溶液和固态51V NMR从V2O5和VO2前体实时合成V2O5·nH2O纳米片。溶液状态51V NMR表明，水溶液中主要含有十钒酸盐阴离子[H2V10O28] 4-和水合二氧钒酸盐阳离子[VO2·4H2O] +，并且在剥离过程中形成十钒酸盐，而[VO2·4H2O的量] +保持恒定。用固态51V NMR监测的固体前驱体V2O5的转化率，当VO2以单斜晶形式出现时开始。干燥的V2O5·nH2O纳米片由于分离的V4 +含量少而具有弱顺磁性。它的固态51V信号不到V2O5的20％，是由抗磁性的V4 +或V5 +引起的。这项研究表明，实时NMR技术可作为强大的分析工具，将散装材料剥离成纳米片。对这一过程的更深入了解将为定制这些重要材料铺平道路。