Two-dimensional Cu nanostructures for efficient photo-catalytic degradation of methylene blue

This work reports the synthesis of stable oxidation-resistant two-dimensional copper (Cu) nanostructures using non-toxic reducing agents and a rapid and simple chemical reduction technique by replacing conventional solvothermal methods. The formation of two-dimensional Cu nanostructures such as Cu nanosheets was successfully observed by tuning the sodium hydroxide (NaOH) and surfactant (CTAB) concentrations during the synthesis process. It has been observed that a high concentration of NaOH (∼2 M) is essential to produce stable Cu nanosheets through the oriented attachment mechanism. The morphology of Cu nanosheets was characterized using a transmission electron microscope. Cu nanosheet phase purity and thickness were analysed using XRD and AFM techniques. Moreover, these Cu nanosheets exhibited efficient photocatalytic activity in degrading the methylene blue (MB) dye from synthetic wastewater. The large surface area associated with Cu nanosheets and their two-dimensional structure helps to enhance the photocatalytic activity and MB dye degradation upon solar and UV light irradiation as compared to zero and one-dimensional Cu nanostructures. Almost 95% degradation efficiency has been successfully observed by irradiating the MB dye solution under solar light for 20 min. Cu nanosheet powder was also successfully recycled for degrading the MB dye by centrifuging the degraded solution, and the recycled Cu nanosheets exhibit ∼80% degradation under solar light irradiation.