Growth of ZnO Nanorods on Graphitic Carbon Nitride gCN Sheets for the Preparation of Photocatalysts with High Visible-Light Activity

The light photoresponse, the separation of photogenerated charge carriers and the specific surface area are of great importance for the development of semiconductor-based photocatalysts. We report the anchorage of small-sized ZnO nanorods with a length of ca. 38 nm at the surface of graphitic carbon nitride (gCN) sheets. The gCN loading in the ZnO/gCN composites was varied and the materials characterized by TEM, XRD, XPS, BET and UV-vis diffuse reflectance spectroscopy. The ZnO/gCN (10 %) composite exhibits a high photocatalytic activity for the degradation of dyes (Orange II, Resazurin and Reactive Black 5) under visible light irradiation of low intensity (2.5 mW/cm(2)) and for salicylic acid under simulated sunlight irradiation (5 mW/cm(2)). These results are supported by photoluminescence, photocurrent and electrochemical impedance spectroscopy measurements. The photocatalytic activity originates from synergistic effects in ZnO/gCN composites including a high specific surface area (60.4 m(2)/g), an enhanced visible light absorption capacity and the charge carriers separation. The ZnO/gCN photocatalyst exhibits a high stability and could be reused up to ten times with no loss of efficiency. A mechanism is proposed for the degradation of dyes using the ZnO/gCN composites.