Studies On Graphene-based Nanomaterials Modified Electrodes And Their Application In Pesticide Determination

Carbon is the fourth most abundant element on earth. The diversity in bonding makes carbon the most important element in a variety of disciplines. The catenation property that is the ability to form large stable frameworks of interconnecting bonds with different hybridization allows carbon to form innumerable compounds with varying dimensionalities. A recent addition to this large family of carbon allotropes is Graphene, a two-dimensional monolayer of sp2carbon atoms arranged in a honeycomb lattice.Rolling of graphene segments with different boundaries results in carbon nanotubes of varying chiralities. Graphene has also made it possible to understand properties in low-dimension. It has opened huge possibilities in electronic device fabrication and has also shown much promise in replacing silicon-based electronics. A number of fascinating properties including the superconductivity, metal-free magnetism, ballistic electronic propagation, charge-carrier doping, chemical activities and high surface area, have made graphene the material of the21st century. The diverse structural and electronic features as well as exciting applications have attracted theoretical and experimental scientists all over the world to explore this low dimensional material.In the first chapter, I have presented a number of experimental routes to synthesize and characterize one to few layers graphene. I have also presented functionalization of graphene and have studied in detail a number of properties including surface, magnetic properties, electro-sensing and electrochemical capacitors properties.In the second chapter, we demonstrated solid-phase extraction (SPE) of nitroaromatic organophosphate (OP) compounds to graphene/multiwalled carbon nanotubes using electroactive methyl parathion (MP) as a model analyte and graphene/multiwalled carbon nanotubes as sorbent. Combining the SPE and square-wave voltammetric (SWV) analysis opens new opportunities for simple, fast and sensitive analysis of OP compounds.In the third chapter, we describe the preparation, characterization, and electrochemical properties of graphene and zirconia nanoparticles nanocomposite. Because of the strong affinity of zirconia (ZrO2) to the phosphoric group, OP pesticides strongly bind to the electrode surface, and graphene can be used as electrode materials with useful property for electrochemical applications. Graphene and zirconia nanoparticles (GZN) were one-step electrodynamically deposited onto the glass carbon electrode (GCE) by cyclic voltammetry. The electrochemical characterization and anodic stripping voltammetric performance of bound OPs were evaluated using cyclic voltammetric and SWV analysis. A combination of SPE with SWV analysis resulted in a fast, sensitive, and selective electrochemical method for determination of OPs using MP as a representative. The stripping response was highly linear over the MP range of0.05-2.0μg/mL, with a detection limit of0.005μg/mL. The proposed sensor showed good precision and reproducibility, these findings can lead to a widespread use of electrochemical sensors to detect OPs contaminates.