Role of activated carbon on the increased photocatalytic activity of AC/Bi2WO6 coupled materials

• AC/Bi2WO6 coupled systems were prepared by means of hydrothermal synthesis.
• AC increases surface area, visible-light absorption and diminishes band gap values.
• Lower AC contents can favour 3D-hierarchical growth of Bi2WO6.
• Enhanced photocatalytic RhB and Phenol degradation is obtained in AC/Bi2WO6 systems.
• Photocatalytic improvement is not only ascribed to an enhanced adsorption mechanism.

The photocatalytic activities of several Bi2WO6 and TiO2/Bi2WO6 materials with different activated carbon (AC) contents were studied for Rhodamine B (RhB) (and Phenol) photodegradation under UV–vis and vis illumination. A wide characterization of the materials was carried out. The addition of AC strongly affected the Bi2WO6 morphology although not the crystalline phase. Even in the material with the lowest AC content (2 wt% nominal content) a structure with hierarchical porosity was formed. AC presence increased the initial reaction rates in the degradation of RhB. An important improvement in the photoactivity under both UV–vis and vis illumination conditions was obtained with the lowest AC content (2 wt%) when compared to the pristine material Bi2WO6 or to the systems with higher AC additions. AC/TiO2/Bi2WO6 materials were also improved in comparison to the TiO2/Bi2WO6 heterostructure without carbon. The improvement cannot be only ascribed to adsorption capability and surface area effects. A mechanism explaining the role of AC on the photocatalytic activity improvement is proposed.

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