Influence of the synthesis route on the electrocatalytic performance for ORR of citrate-stabilized gold nanoparticles

Citrate-stabilized gold nanoparticles (AuNPs) were synthesized by two different citrate-based reduction methods, namely a one-pot wet chemical synthesis (Turkevich method) and seed-mediated growth (Bastús method). Although both types of AuNPs produce similar surface plasmon resonance bands and have a similar particle size and shape, the NPs obtained by the Turkevich method show significantly higher crystallinity. Static and dynamic electrochemical analysis using both types of AuNPs for the oxygen reduction reaction (ORR), under alkaline conditions, confirmed the significant influence of the synthesis route on the resulting onset potentials and maximum intensities in ORR electrocatalysis. These results were attributed to the higher percentage of Au(100) facets and the greater number of active sites on citrate-stabilized AuNPs obtained by the Turkevich method. Underpotential deposition of lead and electrochemical active surface area (ECSA) analysis further confirmed the importance of the crystalline facets in the performance of the AuNPs as electrocatalysts. This study demonstrates the influence of the synthesis route on the electrocatalytic activity of AuNPs, despite using the same starting reagents.