Investigation of the effects of ethanolamine, 2-mercaptoethanol and citrate as capping agent and heteroatom source on ethylene glycol oxidation activity of heteroatom-doped reduced graphene oxide nanocomposites decorated with gold nanoparticles

Abstract

In this study, ethanolamine and 2-mercaptoethanol were tested for the first time as capping agents and heteroatom sources in the preparation of heteroatom-doped reduced graphene oxides (Au/E@rGO and Au/M@rGO) decorated with Au nanoparticles that can be used as catalysts in ethylene glycol (EG) fuel cells. The performance of the composites was compared with the composite prepared at the same conditions using sodium citrate dihydrate (Au/C@rGO), a widely used capping agent in the literature. The average particle size of Au nanoparticles in Au/E@rGO, Au/M@rGO, and Au/C@rGO were calculated as 10.55 ± (5.10) nm, 5.82 ± (2.35), and 3.36 (±1.02 nm) based on the TEM analysis, respectively. Amounts of Au loaded to Au/E@rGO, Au/M@rGO, and Au/C@rGO were determined as 36.50 (±0.51) %, 39.04 (±1.13) %, and 27.66 (±0.08) %, respectively. The EG oxidation performance of Au/E@rGO was 5 and 14 times higher than that of Au/C@rGO and Au/M@rGO. Chronoamperometry measurements showed that Au/E@rGO, Au/C@rGO, and Au/M@rGO catalysts retained 18.72%, 7.31%, and 4.06% of their initial currents, respectively, revealing that Au/E@rGO maintained its stability significantly compared to Au/C@rGO and Au/M@rGO. Repetitive cyclic voltammetry measurements also verified the high stability of Au/E@rGO in EG oxidation. The results showed that ethanolamine can be used as a potential capping and N-doping agent in the preparation of carbon structures containing Au nanoparticles that can be used in fuel cells.