WO3 Quantum Dots Decorated GO/Mg‐doped ZnO Composites for Enhanced Photocatalytic Activity under Nature Sunlight

Graphene oxide/Mg‐doped ZnO/tungsten oxide quantum dots composites (WQGOMZ) were prepared through co‐precipitation method, and were studied by X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS), Fluorescence spectra (FL), and UV–vis diffuse reflection spectra. Furthermore, the photocatalytic activity of resultant WQGOMZ was evaluated under nature sunlight. Experimental results showed that WO3QDs can remarkably heighten the photocatalytic activity of GOMZ composite, in which is nearly 6.58 times higher than that of GOMZ composite. Simultaneously, WQGOMZ composites possess optical memory ability and maintain high photocatalytic stability for more than 40 days. The enhanced photocatalytic activity and optical memory ability are attributed to the effective synergistic effect between ZnO and WO3QDs. Graphene can facilitate the separation of photogenerated electron‐holes pairs. Under light illumination, the photogenerated electrons are transfered to WO3 QDs conduction band, and are stored in WO3 QDs crystal, producing the structure of ·WO3–. In the dark, the structure of ·WO3– can release the stored photogenerated electrons, and transfer to the crystal structure of WO3, keeping the photocatalytic activity in the dark. Hence, WO3 QDs improve the photocatalytic activity of GOMZ composite significantly, and endow the optical memory ability.