Versatile inorganic–organic hybrid WO_x–ethylenediamine nanowires: Synthesis, mechanism and application in heavy metal ion adsorption and catalysis

Inorganic–organic hybrid WO_x-ethylenediamine (WO_x–EDA) nanowires have been produced by a simple, low-cost and high-yield solvothermal method. These WO_x–EDA hybrid nanowires have unique lamellar mesostructures with an alternate stacking of an interconnected [WO₆] octahedral layer and a monolayer of ethylenediamine molecules. This hybrid structure integrated the functionality of ethylenediamine with the stability of the WO_x frameworks. In situ synchrotron-radiation X-ray diffraction is used to elucidate a possible formation mechanism of the hybrid WO_x–EDA. The nanowire morphology, lamellar structure and abundant functional amino groups endow them with versatile abilities. For example, in heavy metal ion adsorption the WO_x–EDA nanowires display exceptional adsorption capabilities of 925 mg·g^–1 for Pb²⁺ and 610 mg·g^–1 for UO₂²⁺. The nanowires also show outstanding stability and activity as a heterogeneous base catalyst in the Knoevenagel condensation reaction at room temperature. The catalyst can be recycled and reused for 20 cycles with nearly 100% yields. This study provides a new strategy to design inorganic–organic hybrid materials, and offers a multifunctional material that is a highly efficient adsorbent and sustainable catalyst.