Preparation of graphene nanocomposites for anticorrosion and sensors

Abstract

This dissertation focused on the development of graphene (GO) nanocomposite coating to improve various substrate properties for the sensor application, which is divided into 2 main parts. The first part is the development of GO incorporated into electroless nickel phosphorus (NiP) coating to improve the properties of metal for electrochemical sensor application. Nickel phosphorus – titanium dioxide sol – reduced graphene oxide (NiP-TiO2 sol -RGO) coated surface was successfully prepared by one-pot electroless deposition on the steel substrate. The results show that the homogeneously formation of water-repellent RGO film covering on the coated surface leading to improve the corrosion resistance and high electrical conductivity of NiP-TiO2-RGO coated steel. The second part is the development of GO nanocomposite coated textile substrates to enhance the analytical performances of non-invasive colorimetric sensor. GO nanocomposite was incorporated on textile substrates including fabric and thread by coating and padding. The cotton fabric based sensor was successfully fabricated for sweat pH and lactate detection and it can directly apply onto the human skin for the simultaneous detection of pH and lactate during the physical exercise. The pH indicator gradually changed from red to blue as the pH increased, whereas the intensity of the purple color increased with the concentration of lactate in the sweat which can indicate the sweat pH in a range of 1-14 and the lactate level of 0-25 mM. As for the textiles, thread has been developed for non-invasive glucose and urea sensor. Thread is a promising microfluidic device for biosensor due to low volume of reagent and sample, fast reaction time and high sensitivity. This sensor can be used to identify the cut-off level of glucose (0.3 mM) and urea (65 mM) in human sweat. This sensor might be incorporated into clothes and accessories for the real-time and continuous monitoring of sweat biomarkers. This platform opens a new approach for non-invasive diagnosis in healthcare and it will be integrated with clothes and apparels for the users in the near future.