Enhancement photocatalytic activity of the graphite-like C₃N₄ coated hollow pencil-like ZnO.

The pencil-like ZnO hollow tubes with 9-12 μm in length, 350-700 nm in width, 200 nm in wall thickness coating with g-C3N4 have been prepared via a chemical deposition process. As compared with uncoated ZnO or g-C3N4, these g-C3N4/ZnO composites showed the enhanced photocatalytic activity which can be attributed to the heterojunction structure. Furthermore, it is worth pointing out that the weight ratios of g-C3N4 to ZnO (g-C3N4/ZnO) played a significantly influence on the photodegradable properties. With increasing the mass ratio, the photocatalytic activity increased firstly and then decreased after reaching to an optimal photocatalytic performance. It can be inferred that the appreciation of g-C3N4 on the ZnO surface can improve the contact area which resulted in high separation of electrons and holes. However, excessive g-C3N4 may hinder the electrons transferring from the g-C3N4 to ZnO, and thus worse its photocatalytic performance. In our study, the g-C3N4/ZnO sample prepared with 10 wt% of g-C3N4 exhibited the optimal photodegradable efficiency which 94% of Rhodamine B (RhB) has been degraded just in 2 h.