Synthesis of a nanocomposite based on the modification of graphene oxide with cysteamine-capped gold nanoparticles and investigation of its use as anode catalyst in ethylene glycol fuel cells

Abstract

• A nanocomposite was synthesized using cysteamine-capped Au nanoparticles and rGO. • Cysteamine behaved as a linker, a stabilizer and a reducing agent in the synthesis. • Au/Cys@rGO was tested as a catalyst layer for the first time in EG fuel cells. • Au/Cys@rGO showed high activity towards the electrochemical oxidation of EG. • The stability of Au/Cys@rGO was much higher than that of Au@rGO. In this study, cysteamine-capped Au nanoparticles (Au/Cys) were used for the first time for the modification of graphene oxide (GO) to form a nanocomposite (Au/Cys@rGO) that could be used in ethylene glycol (EG) fuel cells. The Cys has three important functions in the preparation of the targeted nanocomposite; i) preventing the aggregation of Au nanoparticles as a stabilizer, ii) presenting N and S heteroatoms for doping of rGO, iii) enabling the reduction of GO to form rGO. The Au nanoparticles modified rGO (Au@rGO) was also prepared for comparison. The characterization studies showed that the presence of Cys allowed the homogeneous and uniform distribution of Au nanoparticles on rGO. The average particle sizes of Au nanoparticles in Au/Cys@rGO and Au@rGO were calculated as 10.36 (±3.21) and 54.80 (±30.13) nm, respectively. The amounts of Au loaded to Au/Cys@rGO and Au@rGO were measured as 38.19% and 41.72%, respectively. The cyclic voltammograms of EG showed that the activity of Au/Cys@rGO in the oxidation of EG is 37.33 times higher than that of Au@rGO, showing the prominent effect of Cys. The high activity and stability of Au/Cys@rGO over Au@rGO demonstrates the potential of this nanocomposite to be used in EG fuel cells.