Graphene Oxide-Based Nanocomposites for Environmental Protection

Abstract

The exponentially increasing chemical pollutants and highly resistive pathogens have made it a necessity for the development of an innovative, multifunctional material. Graphene oxide (GO) and silver nanoparticles (AgNPs), both exhibit excellent antibacterial, sensing, and catalytical properties thereby being the ideal choice to investigate the integration of the nanomaterial into environmental applications. Various methods can be opted to synthesize GO-based nanocomposites however each technique has its benefits and drawbacks. Therefore, this thesis explores an improved Hummer’s method and Pulsed Laser Ablation in Liquid (PLAL) for the fabrication of high-quality GO and surfactant-free graphene oxide-silver (GO-Ag) composites, respectively. In a simple and fast PLAL procedure, a pure silver target plate, immersed in fully dispersed GO solution, is ablated by an Nd-YAG nanosecond laser. Thereby forming a highly stable colloidal composite without the use of any chemical agents or harmful by-products. The laser parameters had been optimized to control the specific characteristics of the GO-Ag composite for enhancing the antibacterial and sensing properties. As such the ablation process was carried out with a 1064 nm laser for varying time and varying energy. After various trials, the optimal parameters were deduced as 140 mJ energy and 10 mins. Moreover, the synthesized materials were confirmed by multiple diagnostic techniques including FTIR, UV-Vis spectroscopy, SEM, EDS, Raman, Zeta potential analysis, and XRD. Thereby giving an insight into the chemical properties, structure, and morphology of the fabricated composites. Subsequently, the antibacterial activity and potential in SERS were evaluated. The results demonstrated that GO-Ag composites have superior antibacterial activity, SERS xvi capability, and stability compared to the individual components; GO and Ag. Additionally, the cubic shape GO-Ag micro-composite had better antibacterial performance than that of the spherical GO-Ag nanocomposite. Thus GO-Ag composite with optimized properties is a promising multifunctional material for environmental protection.