Vanadyl hydroxide (VOOH) nanosheets have been synthesized for the first time using commercial vanadium pentoxide (V₂O₅) as vanadium source by a facile one-step hydrothermal reaction. The morphology and crystal structure of VOOH can be controlled simply by adjusting the ratio of ethylene glycol (EG) to deionized water (H₂O) in the hydrothermal reaction. The electrochemical performance of the VOOH nanosheets as electrode material for supercapacitors was investigated in 1 mol L⁻¹ LiClO₄/propylene carbonate, and it was found that the highest specific capacitance of the VOOH nanosheets is 323 F g⁻¹ at a current density of 0.2 A g⁻¹ due to their higher specific surface area and electrochemical activity, which is 3 times large than that of VOOH nanoparticles and the reported VOOH hollow spheres. Meanwhile, the VOOH nanosheets also show a good cycling stability with a capacitance retention of 70% after 2000 cycles at a current density of 2 A g⁻¹. This work demonstrates that the VOOH nanosheets, as a new member of two-dimensional materials family, not only can be simply synthesized by hydrothermal method, but also show an excellent electrochemical performance for supercapacitor applications.

氢氧化钒（VOOH）纳米片是首次使用商品五氧化二钒（V ₂ O ₅）作为钒源，通过简便的一步水热反应合成的。通过调节水热反应中乙二醇（EG）与去离子水（H ₂ O）的比例，可以简单地控制VOOH的形态和晶体结构。在1 mol L ^-1 LiClO ₄ /碳酸亚丙酯中研究了VOOH纳米片作为超级电容器电极材料的电化学性能，发现VOOH纳米片的最高比电容为323 F g ^-1。 0.2 A g ^-1由于它们的比表面积和电化学活性更高，是VOOH纳米颗粒和报道的VOOH中空球的3倍。同时，VOOH纳米片还表现出良好的循环稳定性，在2A g ^-1的电流密度下2000次循环后的电容保持率为70％。这项工作表明，VOOH纳米片作为二维材料家族的新成员，不仅可以通过水热法简单地合成，而且在超级电容器应用中显示出出色的电化学性能。