Fabrication of a plasmonic sensor for surface-enhanced Raman spectroscopy using electroless deposition of Ag with hypophosphite

Surface-enhanced Raman spectroscopy (SERS) provides insights into electrode reaction processes due to its high selectivity towards the interface. It is necessary to ensure a stable and inexpensive supply of sensors to make this method more widely applicable. Techniques based on electrochemistry are efficient and suitable for mass manufacturing. In this research, two electroless processes for depositing Ag nanoparticles (NPs) on a glass substrate for sensor fabrication are discussed: one using ascorbic acid, the other hypophosphite. Specifically, the process using hypophosphite was achieved by forming Pd nuclei in the activating process. It turned out that when the ascorbic acid sensor is applied, undesired SERS signals originating from the reductant appear. By contrast, the hypophosphite sensor greatly reduces the unwanted signals. The optimized plasmonic sensor can achieve in situ SERS observation of electrochemical reactions without being restricted by electrode material and morphology.