Tryptophan-Stabilized Au-Fe_xO_y Nanocomposites as Electrocatalysts for Oxygen Evolution Reaction

Au-Fe_xO_y nanocomposites with a variable gold-to-iron ratio were stabilized with l-tryptophan. The synthetic methodology is based on the facile redox reaction between Au(III) and Fe(0) in the presence of gold nanoparticle as a seed at room temperature in an aqueous medium. The synthesis results in the deposition of Au nanoparticles on the surface of iron oxide layers. Composition variation in the nanocomposites was obtained by controlling the seed amount and reducing agent. These nanocomposites are used as electrocatalysts for the thermodynamically unfavorable oxygen evolution reaction (OER) from water. Among the nanocomposites, the most efficient OER activity was observed from the nanocomposite 12. The content of iron with respect to gold is at the maximum in the nanocomposite, which was obtained from the reaction with a minimum seed concentration and maximum reducing agent.