Photocatalytic Degradation of Methylene Blue Using a New Graphitic Carbon Nitride Nanocomposite

Graphitic carbon nitride (g-C3N4) is a metal-free semiconductor compromised of carbon and nitrogen. g-C3N4 possesses a unique 2D structure, visible light sensitivity, high chemical stability and tunable electronic structure which has attracted worldwide research interest [1]. Due to its band gap of 2.7 eV, it could be easily used in environmental applications and photocatalytic fields. Furthermore, its excellent structure makes it easy to couple with various functional materials to enhance the performance in order to be widely employed in photocatalytic degradation of organic pollutants like methylene blue dye [2]. The present work demonstrates the preparation of nickel oxide/graphitic carbon nitride (NiO/ g-C3N4) by an innovative method. In accordance with the principles of green chemistry, nanostructures were synthesized by natural stabilizers like glucose in a soft template method using reverse micelles for the first time. The electronic and chemical structure, surface compositions, optical properties and morphologies of the prepared NiO/g-C3N4 were well characterized using SEM, TEM, FTIR, XRD, EDX as well as nitrogen absorption and desorption. Subsequently, the photocatalytic activity and stability of NiO/g-C3N4 were evaluated by the degradation of methylene blue dye under the visible light irradiation, revealing that the composites exhibit enhanced photocatalytic activity compared to pure g-C3N4 and NiO. This can be explained by the efficient separation of the photo-generated electron-hole pairs due to the carrier transfer between g-C3N4 and NiO. As a consequence, an increased number of electrons and holes are available for the photocatalytic reaction to decompose aqueous organic pollutants effectively.