High selective photo-oxidation of cyclohexanol into cyclohexanone by W18O49 - Graphene oxide composite

Abstract

The efficient photooxidation of cyclohexanol to cyclohexanone under mild conditions presents significant challenges due to its low efficiency and unwanted by-products. In this study, we present a simple and scalable method to prepare a graphene oxide (GO)-tungsten oxide (W₁₈O₄₉) composite that overcomes these limitations. By combining ultrathin oxygen-vacancy containing W₁₈O₄₉ nanowires with GO sheets, we create a type II photocatalyst that enhances light absorption, minimizes electron-hole recombination, and selectively converts cyclohexanol to cyclohexanone. This design leverages the distinct advantageous characteristics of both materials, avoiding the aggregation of W₁₈O₄₉ nanowires and GO sheets while enhancing the absorption of reactants. Under ambient conditions and simulated solar light irradiation, the composite with a mass ratio of W₁₈O₄₉ to GO being 8:1 achieved 99.5 % selectivity for cyclohexanone with a conversion rate of 2.56 %, which is 1.83 times greater than standalone W₁₈O₄₉. The investigation into the selective photocatalytic oxidation mechanism was conducted through photoelectric measurements, band energy spectrum analysis, and active radical trapping experiments. The findings of this study demonstrate improvements in cyclohexanol adsorption and the charge separation by utilizing GO-W₁₈O₄₉ materials, ultimately leading to a strong preference for cyclohexanone under gentle conditions. This groundbreaking method holds significant promise for the advancement of photocatalysis technology.