Facile construction of leaf-like WO3 nanoflakes decorated on g-C3N4 towards efficient oxidation of alcohols under mild conditions

Abstract

Herein, a well-defined nanostructure with leaf-like WO₃ nanoflakes decorated on g-C₃N₄ was constructed via a facile impregnation and subsequent annealing method. The prepared WO₃/g-C₃N₄ exhibited excellent catalytic activity for the selective oxidation of alcohols under mild conditions, and satisfactory yields to the corresponding carbonyl compounds were achieved without using non-green additives and organic solvents. It was found that the enhanced catalytic activity could be attributed to the enlarged specific surface area, the well-defined nanostructure, and the strong interactions between WO₃ and g-C₃N₄. The distribution of WO₃ nanoflakes on the g-C₃N₄ support increased the number of catalytically active sites for this reaction. XPS analysis suggested that a synergistic electron effect occurred because of the electron transfer from g-C₃N₄ to WO₃. Moreover, the effects of reaction temperature, reaction time, oxidant amount and catalyst dosage on catalytic activity were investigated. Recycle studies showed that the catalyst could be readily recovered and no obvious decrease in catalytic efficiency was observed after seven cycles. The present catalytic system can afford a wide substrate scope for both aryl and alkyl alcohols with superior conversion and selectivity. Also, a plausible reaction mechanism was proposed to better illustrate the catalytic process. This work might provide a facile construction of a well-defined WO₃/g-C₃N₄ catalyst for the selective oxidation of alcohols using a sustainable approach.