Visible Light Photocatalysis with c-WO3–x/WO₃×H₂O Nanoheterostructures In Situ Formed in Mesoporous Polycarbosilane-Siloxane Polymer

In recent years, there have been significant efforts to find novel photocatalytic materials with improved properties. Thus, there is an active ongoing search for new materials that can operate at a broad range of wavelengths for photocatalytic reactions. Among photocatalytically active semiconductors, considerable attention has been given to tungsten oxide with a band gap of E(g) ≈ 2.6 eV, which provides the opportunity to harvest visible light. In the present work, we report on a one-step synthesis of c-WO(3-x)/WO3×H2O nanowhiskers dispersed in a hydrolytically stable mesoporous polycarbosilane-siloxane ([-Si(O)CH2-]n) matrix. The as-synthesized nanocomposites possess high photocatalytic activity for the degradation of methylene blue (MB) under visible light irradiation. The enhanced photocatalytic activity is due to (i) the reduction in the electron-hole recombination rate because of the reduced dimensions of nanowhiskers, (ii) more efficient consumption of photogenerated electrons and holes as a result of the high surface-to-bulk-ratio of the nanowhiskers, and (iii) better electron-hole pair separation due to the formation of c-WO(3-x)/WO3×H2O nanoheterostructures.