Ultrathin 2D2D WO3-x-C3N4 heterostructure-based high-efficiency photocatalyst for selective oxidation of toluene

Abstract

Photocatalytic oxidation of toluene for the organic synthesis of value-added benzaldehyde has attracted great attention in recent years. However, activation of CH bonds and selective production of benzaldehyde under mild green conditions remains a great challenge. Herein, a series of two-dimensional (2D) ultrathin heterostructure-based components (WO_3-x-C₃N₄ nanosheets), fabricated by coupling oxygen-deficient WO_3-x with amorphous C₃N₄ via a simple electrostatic self-assembly method, was demonstrated as high-efficiency photocatalysts to produce benzaldehyde in the presence O₂ as oxidant at room temperature. Under optimal conditions, the prepared 10WCN sample (10 wt% WO_3-x-C₃N₄) exhibited improved photocatalytic oxidation ability with a good benzaldehyde selectivity (96 %) and high benzaldehyde yield (2738.6 μmol g⁻¹ h⁻¹) within 6 h, which is 6.6 and 3.3 times than that of pure WO_3-x (412.5 μmol g⁻¹ h⁻¹) and C₃N₄ (835.7 μmol g⁻¹ h⁻¹). The enhanced photocatalytic performance was due to the constructed 2D type II heterojunction and abundant oxygen vacancies (OVs), contributing to the photoinduced carriers' separation and migration efficiently. This work indicates the synergistic effect of defect metal oxides and 2D ultrathin sheet-to-sheet heterojunctions in photocatalytic hydrocarbon conversion.