ZnO/carbon quantum dots heterostructure with enhanced photocatalytic properties

Zinc oxide (ZnO)/carbon quantum dots (CQDs) heterostructure has been prepared via a sol–gel approach combined with a spin-coating processing and the CQDs obtained by a simple method. The samples are characterized by using transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infra-red spectroscopy, photoluminescence (PL) emission spectroscopy and photocurrent–voltage curves, and the photocatalytic property of this heterostructure has also been investigated by using Rhodamine B as a test substance. The results revealed that some kind of electronic interaction between ZnO and CQDs is formed. This interaction contributes to both the improvement of charge separation and the reduction of charge recombination, and thereby enhances the photocatalytic property. The degree of photocatalytic activity enhancement strongly depends on the layers of CQDs coating on the surface of ZnO layer. The heterostructure with 4 layers of CQDs shows the highest photocatalytic activity, which is about 3 times as that of pristine ZnO.