Large-scale synthesis and electrochemical properties of hydrated tungsten trioxide-based hierarchical microstructures

Hierarchically self-assembled micro-/nanostructures of o-WO3.1/3H2O were successfully synthesized by surfactant-assisted hydrothermal reaction at 180 °C for 76 h in acidic medium (pH = 1). The effect of the surfactant n-alkyl chain length CnH(2n+1)SO4Na (with n = 10, 12 and 14) on the morphology and the crystallite sizes were investigated. The as-synthesized samples were characterized by different techniques. When sodium decylsulfate is used, agglomerates of irregular particles of orthorhombic WO3.1/3H2O (o-WO3.1/3H2O) are obtained. The sample obtained by the use of sodium dodecylsulfate, consists of o-WO3.1/3H2O microdisk-like structure formed by self-assembled nanosheets (with an average thickness of about 20 nm), resembling chrysanthemum flower. O-WO3.1/3H2O microsheres-like 3D architectures constructed from 2D sheets intervened out-of-order, resembling sand roses, are obtained with sodium tetradecylsulfate as surfactant. The prepared o-WO3.1/3H2O hierarchical assemblies are used as electrode materials to study the electrochemical properties in propylene carbonate containing 1 M LiClO4 solution, by cyclic voltammerty. It was found that o-WO3.1/3H2O microdisks and microspheres exhibit reversible redox behavior accompanied by reversible intercalation/deintercalation of Li+ cations into crystal matrix. It has been revealed also that higher currents were measured for microdisk-like structure and higher diffusion coefficient of Li+ (2.93 × 10−10 cm2/s) compared to microsphere-like structure (2.02 × 10−10 cm2/s).