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
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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.
