Systhesis Of Graphene-based Nanomaterials And Its Composites Application In Photocatalysis

Graphene is the hexagonal arrangement of carbon atoms forming a one-atom thick planar sheet, graphene has ignited tremendous research interest due to its unique properties. In the past few years, there has been an ongoing enthusiasm to the preparation of graphene, kinds of chemical and physical routes were explored to produce graphene, different approaches prefer to fabricate different types of graphene. However, reliable production of single-and few-layers graphene samples in high quality and yield is still a challenge. With these factors in mind, it is easy to see what is needed. We require an alternative, liquid phase process that results in the exfoliation of graphite to give graphene at reasonably high yield. As such, there has been significant interest in the development of a large-scale production method for high-quality graphene.1. Synthesis of single-or few-layer graphene sheets by liquid-phase exfoliation of natural graphite in task-specific alkyl-3-methylimidazolium peroxydisulfate ionic liquids (TSILs) was studied. The coordinated effect of oxidation of the anion and intercalation of the cation in TSILs resulted in the sufficient exfoliation of graphite layers and provided single-or few-layer graphene sheets with a relatively lower concentration of defects and oxygen-containing groups. The obtained graphene combining TiO2 nanowires with the preparation of TiO2/graphene composites, and study its photocatalytic performance of the photocatalytic degradation of Congo red.2. Preparing high-quality graphene sheets by the liquid-phase exfoliation of expanded graphite (EG) in task-specific ionic liquids (TSILs) was developed. The used TSILs contain alkyl-3-methylimidazolium cation that has stronger intercalation in the expanded graphite and peroxydisulfate anions that oxidize the edge of the expanded graphite and facilitate the intercalation of the imidazole cation. Such coordinated attack of the anion oxidation and the cation intercalation resulted in sufficient exfoliation of EG and provides single- and few-layer graphene sheets with fewer defects, lateral extent of more than ten micrometers and higher optical transmittance. The nanocomposites comprising the prepared graphene sheets and P25 exhibit a higher photocatalytic activity for the photodegradation of methylene blue under UV-light.3. Water-soluble graphene quantum dots were prepared by "top-down" cutting method using strong oxidative acids. The ordered graphitic arrays with the finely controlled diameter were particularly chosen as the starting materials, and thus the uniform size of quantum dots can be easily controlled. The prepared GQDs show the remarkable size-independent light-emitting behaviour and can be used as promising metal-free luminescent carbon mateials. Besides, by tuning the oxidation time, we obtain different cabon-based nanomaterial which provided further insight into their cutting process and to stimulate further research into their potential mechanisum.4. The uniform hollow Onion-like graphite ring (OLGR) with high purity were purified and separated from ordered mesoporous graphitic arrays (OMGAs) via a mild approach using oxidizing task-specific ionic liquids, 1-butyl-3-methylimidazolium peroxydisulfate (TSILs, [C4mim]2[S2O8]). The obt ained onion-like graphite ring clearly shows the concentric, quasi-spherical structures with few obvious defects. In addition, TiO2/OLGR nanocomposites were obtained by combining OLGR with TiO2 through a simple hydrothermal method. Remarkably, TiO2/OLGR exhibited an excellent UV-light photocatalytic activity.5. We first synthesized TiO2 nanosperes, and then wrap TiO2 nanosperes with graphene, CuFe2O4 nanoparticle synthesized by sol-gel synthesis dispersed on the surface of graphene. The synthesised CuFe2O4@graphene-TiO2 composites exhibited superior photocatalytic performance. In addition, CuFe2O4 nanoparticle has good magnetic properties, resulting in the catalyst can be repeatedly used easily.