Silver nanoparticle impacts on gold electrode surfaces in flow-injection configuration

Abstract

Flow-injection techniques using nanoparticles are important in several applications. This work reports experimental work on the effect of flow rates on the fate of nanoparticles impacting an electrode surface, in real, commercially available flow systems. Resonance Enhanced Surface Impedance (RESI) and Particle Chronoamperometry were used for monitoring silver nanoparticles (AgNPs) collisions in a FIA format, on gold working electrodes using dodecanethiolate (DDT-AgNP) and (ω-ferrocenylhexanethiolate) silver NPs (FcHT-AgNP). The results are intuitive, showing that factors such as flow rates and ligand electroactivity have significant impact on nanoparticle-electrode collision events. A slow flow rate, (5 μL/min) resulted in the detection of broad spikes, suggestive of large agglomerated particles comprised of 100–150 NPs compared to narrower spikes, comprised of 4–5 NPs detected at higher flow rate (100 μL/min). FcHT-AgNPs, monitored at 5 μL/min, at the electrode held at an oxidising potential for ferrocene, showed spikes suggestive of reduced agglomeration on the surface of the electrodes. The electrode surface recovered following the dwell time of the NP containing solutions on the electrode surface. RESI and CA used in conjunction provide capabilities for isolating capacitive effects from faradaic effects.