The WO3, ZnO, and TiO2 possess strong photocatalytic properties mostly in the UV region of the EM spectrum. These materials have been widely used for the photocatalytic water disinfection, pollutant degradation or renewable hydrogen production. In contrast, these materials have several drawbacks like low specific surface area, decreasing their adsorption ability. To increase the adsorption performance and to perform the aforementioned reactions a nanocomposite with some high surface area materials like activated carbon is preferred.

Thanks

Article Synthesis of multifunctional activated carbon nanocomposite ...

check this , it contains latest updates for uses of carbon based materials

https://www.crcpress.com/Carbon-Nanomaterials-for-Electrochemical-Energy-Technologies-Fundamentals/Sun-Sun-Chen-Liu-Wilkinson-Zhang/p/book/9781498746021

The mentioned semiconducting materials such as ZnO, TiO2, WO3 etc. are used in various photocatalytic reactions, such as photocatalytic degradation of PPCPs and POPs, hydrogen production, and photocatalytic organic synthesis. However, they are wide band gap materials with Eg values varying from 2.9-3.2 eV. Therefore, they experience a drawback, of absorption of light in ultra violet region of solar spectrum. In addition, as Dr. Rayees mentioned that their specific surface area is also low. Since, catalytic reactions occurs at surface of catalysts, therefore, the nanoparticles with low specific surface area are modified with materials which have high adsorption capacity and activated carbon is the best material to be used for adsorption. Anchoring of activated carbon onto Metal oxides surface increases the surface area and therefore, enhance the photocatalytic efficiency.

Thanks

does activated carbon bring the photo catalysis to visible range?

@Million Mulugeta Habtegebrel, yes my dear friend composites of wide band gap semiconductors with activated carbon may increases their visible light photocatalytic performance.

To increase the conductivity of electron generated by light thus reducing the recombination rate of electron hole which is a major factor in photocatalytic activity of metal oxide and sulfide semiconductor materials.