Hydrothermal Synthesis of V[sub 2]O[sub 5]⋅1.9H[sub 2]O Single Crystals with Novel Electrochemical Characteristics

Abstract

The synthesis of V 2 O 5 •1.9H 2 O single crystals from VOSO 4 by chemical oxidation with H 2 O 2 through means of a hydrothermal route is demonstrated. The textural properties of this oxide are characterized by X-ray photoelectron spectroscopy, high-resolution analysis electron microscopy, X-ray diffraction analysis, and thermogravimetric analysis. The novel redox intercalation ability and ion selectivity for the potassium ion among Li, Na, and K ions reveal its promising application potential to K ϩ sensors, high-power rechargeable batteries, and the purification of potassium ions in aqueous media.Divanadium pentoxide and V 2 O 5 -like materials in the crystalline and hydrous forms can be prepared by several chemical routes, such as hydrothermal synthesis, 1,2 sol-gel method, 3-5 electrochemical deposition, 6 and peroxo sol-gel method. 7 These vanadium-based oxides showing distinctive physicochemical properties are widely studied for several applications, e.g., catalysts of chemical reactions 8,9 and Li-ion batteries. 6,10-14 The V 2 O 5 -like materials with a layered structure show the typical redox intercalation ability for various intercalating species, 13,14 and have been considered as an important electrode material in the development of high-energy density Li-ion batteries. 14 Accordingly, the relationship between textural characteristics and physicochemical properties of V 2 O 5 -like materials appears to be an interesting research field in both materials science and chemistry.Layered V 2 O 5 -like materials can be easily prepared from the dissolution of crystalline V 2 O 5 in H 2 O 2 13 or quenching in water, 15 and both crystalline V 2 O 5 and V 2 O 5 -like materials are commercially available. However, to the best of our knowledge, the synthesis of V 2 O 5 single crystals from vanadium precursors in lower valences ͑e.g., V 2 O 3 , VOSO 4 , etc.͒ under a mild chemical environment ͑i.e., hydrothermal synthesis at temperatures р200°C͒ has not been reported to date. In addition, due to the dependence of the redox properties on the crystalline and amorphous forms of V 2 O 5 -like materials, 13-15 developing and controlling their textural characteristics during the synthesis process become important research topics.In this paper, we demonstrate that V 2 O 5 single crystals can be formed from VOSO 4 oxidized with H 2 O 2 through a hydrothermal route under a mild chemical environment ͑i.e., at 180°C for 24 h͒. In addition, the novel redox intercalation ability and ion selectivity of this oxide for the potassium ion among Li, Na, and K ions in aqueous media are systematically compared. The textural properties of this oxide are characterized by X-ray photoelectron spectroscopy ͑XPS͒, high-resolution analysis electron microscopy ͑HR-AEM͒, X-ray diffraction ͑XRD͒ analysis, and thermogravimetric analysis ͑TGA͒. ExperimentalAn aqueous solution of 15 mM VOSO 4 was dropped into 35% H 2 O 2 to oxidize the precursor. V 2 O 5 single crystals were synthesized by a hydrothermal route from this VOSO 4 solution at 180°C for...

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