Amine oxide surfactant-mediated synthesis of plate-based gold nanocrystals with tunable surface wrinkles and their applications in the ethylene glycol oxidation reaction

Abstract

The judicious selection of capping agents has been proven essential for the one-pot synthesis of high-purity two-dimensional noble-metal nanocrystals. In this study, we highlight the synergistic effect of using lauramidopropylamine oxide, a typical zwitterionic surfactant, in conjunction with the quaternary ammonium surfactant octadecyltrimethylammonium chloride. This pairing facilitates the production of Au nanoplates distinguished by their reduced lateral dimensions (i.e., sub-50 nm) and distinctive atomic packing. This ability to vary the structural features enables the Au nanoplates to exhibit enhanced electrochemical activity for the ethylene glycol oxidation reaction (EGOR) in an alkaline medium, characterized by improved reaction kinetics and prolonged cycling stability. DFT simulations suggested that the lower energy barrier of the rate-determining step on Au(211) compared to Au(111) and Au(100) indicates a higher electrochemical activity for the Au(211) surface. The present work underscores the potential of amine oxide-based zwitterionic surfactants in the controlled synthesis of two-dimensional Au nanocrystals, a method that could be potentially adapted for use with other noble metals and/or alloys.