Growth of W18O49/WOx/W dendritic nanostructures by one-step thermal evaporation and their high-performance photocatalytic activities in methyl orange degradation

Abstract

In this work, W₁₈O₄₉/WO_x/W dendritic nanostructures were facilely fabricated by a one-step thermal evaporation method, into which a reduction process at a temperature as high as 1250 °C was deliberately inserted. In the dendritic nanostructure, W₁₈O₄₉ nanowires acted as tree trunks, W nanoparticles acted as fruits grown on the tree trunks and amorphous WO_x layers acted as self-assembly bonds between them. In the reduction process, dangling bonds and defects were expected in this integrated nanostructure, greatly enhancing its optical absorption covering the full spectrum (200–2500 nm). High-performance degradation of methyl orange using these dendritic nanostructures under vis-NIR irradiation (with wavelength ≥550 nm) was achieved for the first time, with good cycling durability in view of no deterioration after ten reaction cycles, which stemmed from their enhanced optical absorption and boosted the separation of photoexcited carriers distinctively by the interfacial tunneling effect of electrons owing to the existence of the two-dimensional WO_x bond layer (1–2 nm). This dendritic nanostructure holds great promise for waste-water treatment and organic dye degradation.