Synthesis, characterization and determination of the activities of functionalized gold/reduced graphene oxide nanocatalysts for direct ethylene glycol fuel cells

In this thesis, nitrogen (N), nitrogen-sulfur (NS) and sulfur (S) doped reduced graphene oxide (rGO) supported gold nanoparticles (Au NPs) were synthesized using hydrothermal and thermal methods for use as anode catalysts in direct ethylene glycol (EG) fuel cells. The performance and stability of these nanocatalysts for ethylene glycol oxidation were evaluated. Electrochemical characterization was conducted using cyclic voltammetry (CV), chronoamperometry (CA) and structural characterization was performed using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) etc. In the hydrothermal method, ethanolamine, cysteamine, and 2-mercaptoethanol were used as both capping and doping agents and sodium citrate used as capping agent. For activity comparison, rGO supported Au nanocatalysts were synthesized without using any stabilizing and doping agents. The highest activity (58.50 mA/cm2) in ethylene glycol oxidation was achieved with the catalyst prepared in the presence of ethanolamine. This value is 65 times higher than the catalyst prepared without using any doping or stabilizing agents. The current density values obtained showed that the activities of the prepared catalysts depended significantly on the type of doping agent used. In the thermal method, 1-octanethiol was used as the stabilizing agent, and urea (N), thiourea (NS) and sodium bisulfite (S) were used as doping agents. The current density of ethylene glycol increased by 1.92 times when urea was used as a doping agent compared to the catalyst prepared without using any doping agent. The obtained results showed that various parameters such as synthesis temperature and doping ratio significantly affected the activities of the prepared catalysts.