Electrochemical Deposition of Silver Nanoparticle Assemblies on Carbon Ultramicroelectrode Arrays

Silver nanoparticle (AgNP) assemblies on electrode surfaces are widely utilized in electrochemical energy storage applications, (bio)sensor development, and electrocatalysis. Among various methods of nanoparticle synthesis, electrochemical deposition offers precise control over experimental conditions, achieving low-nanoscale (<10 nm) particles with uniform size distributions. In this study, we report the electrodeposition of AgNPs on carbon ultramicroelectrode arrays (CUAs), a unique electrode platform consisting of carbon-based ultramicroelectrodes fashioned in an array geometry. The influence of electrodeposition parameters, including silver ion concentration, deposition time, and applied potential on AgNP formation was explored through extensive electrode characterization. Scanning electron microscopy results indicated that more negative, reductive deposition potentials resulted in higher AgNP counts of smaller sizes. Macro-sized, planar electrode platforms often employed in previous nanoparticle electrodeposition studies require minute-long deposition times and millimolar Ag+ concentrations. Our work demonstrates that sufficient AgNP formation on CUAs can be achieved with lower silver concentrations (50–100 µM) and shorter deposition times (15–30 s), due to the enhanced mass transport at the CUA surface from the radial diffusion behavior. The deposited Ag was quantified at 1100 ± 200 nmol cm–2, aligning with the observed electrocatalytic activity of the AgNP-modified CUAs for hydrogen peroxide reduction. These findings underscore the importance of studying AgNP electrodeposition conditions for unconventional electrode surfaces.