One-Step, Solventless, and Scalable Mechanosynthesis of WO₃·2H₂O Ultrathin Narrow Nanosheets with Superior UV–Vis-Light-Driven Photocatalytic Activity

Abstract

Environmentally benign, high-yield, cost-efficient, and facile fabrication of ultrathin two-dimensional (2D) nanomaterials has been a bottleneck restricting their massive and extensive applications. In this work, a one-step, solvent-free, and easily scalable approach for the preparation of WO3·2H2O ultrathin narrow nanosheets has been proposed for the first time, which is based on solid-state mechanochemical reaction between sodium tungstate dihydrate (Na2WO4·2H2O) and oxalate dihydrate (H2C2O4·2H2O) at ambient temperature. The resulting WO3·2H2O presents uniform rectangular nanosheets with a typical length of 50–80 nm, a width of about 10 nm, and a thickness of 5.67 nm. Phase evolution in the synthetic process of WO3·2H2O ultrathin narrow nanosheets was investigated by X-ray diffractometry. Their formation mechanism was also rationalized on the basis of in situ precipitation and preferential growth of ionized WO42– on the surface of mechanically exfoliated oxalate nanosheets. The WO3·2H2O ultrathin narrow nanosheets exhibit excellent adsorptive and UV-to-vis-light-driven photocatalytic properties with adequate recyclability in the removal of Rhodamine B (RhB) from aqueous solution, and also show promise for potential applications in photoelectronic devices, gas sensors, supercapacitors, lithium-ion batteries, and other environmental remediation.