Title : Synthesis, characterization and applications of NEVHCS LSC of GO from waste pencil leads (WPL)
As a reliable precursor and derivate of graphene, graphene oxide (GO) (with a few layers) has received wide attention in recent years. However, the synthesis of GO (>10 nm) in an economical and efficient way from a low-cost renewable source remains a great challenge. More specifically, a high quality, low cost, nearly defect free, highly dispersible, naked eye viewed honeycomb structured (NEVHCS) liquid single crystals (LSC) of GO (graphene oxide) is still now rare and a big challenge to synthesize, which has been successfully done using waste pencil leads as raw material following improved modified Hummer’s method. A gradual increase of RPM during centrifugation was used to purify and optimize the final pH range of the graphene oxide (GO) solution before crystallization and drying. This modification is not only successful to get defect free NEVHCS mega-sized crystalline product but also to achieve GO with a few layers (up to 3 nm) increasing the reaction yield regarding the volume and surface area in comparison with conventional Hummer’s method. It was thereafter converted to rGO (reduced GO) using an aqueous leaf extract of bryophyllum pinnatum as reducing agent. The morphology and structure of both GO and rGO were characterized by different physico-chemical, microscopic, spectroscopic, and electrochemical methods. Moreover, the rGO was applied as nanocomposite with copper oxide (Cu2O) for the electrochemical conversion of CO2 into useful products. These findings would introduce and encourage researchers of this field to synthesize nearly defect free NEVHCS graphene NMs to achieve more efficient graphene-based products eliminating its inherent defect problem. However, the NEVHCS highly crystalline GO would be a very simple but great practical evidence to confirm the formation of quasi perfect crystals of GO instead of confirming with highly expensive electronic microscope. Furthermore, this green, ultralow-cost, improved approach of synthesis shows good prospects for large- scale commercial production and applications of high-quality GO and its derivatives.
- Since its complete isolation and characterization in 2004 until now it is not possible to figure out the honey-comb structure of graphene without the help of high-resolution microscope. From my presentation, the audiences could be able to introduce first time with the Naked Eye Viewed (NEV) honey-comb structure (HCS) of graphene in GO.
- Here, I will describe the detailed method of synthesis of naked-eye visible highly pure large size liquid crystals of GO from waste pencil lead and its characterization by different physicochemical, spectroscopic, microscopic, and electrochemical techniques. I will also present the green conversion of GO to rGO and then apply prepared rGO for the electrochemical reduction of CO2. The scientific community working with graphene or GO would be able to learn how to prepare, characterize and apply the defect free, highly quality NEVHCS GO. This knowledge would encourage them to avoid the commercial graphene NMs. Because they often use those graphene NMs remaining mostly in dark regarding their quality, surface area or surface to volume ratio which is very important to evaluate any nanomaterials. Especially, in case of graphene, the thickness of the layer is the most vital issue. Unfortunately, world renowned commercial manufacturers are supplying the NMs claiming as graphene with few nm but practically those are not like that as they claimed. Even those NMs are either defect free or how much defect present in them is not possible to know without going through a tedious, time consuming and highly expensive microscopic characterization. As a result, the optimization regarding the performance of their graphene-based products or devices remain practically undone that is a great obstacle for the commercialization of graphene-based technologies.
- I hope the method for the synthesis of NEVHCS liquid single crystal (LSC) of GO would solve those inherent limitations in the field of graphene-based Nanoscience and Nanotechnology. The interdisciplinary researchers such as Chemist, Physicist, Biochemist, Microbiologist, Engineer, Material scientists who are working with graphene would be benefited as well from my research findings. The students, colleagues of the participants could also be updated their knowledge by sharing with them.