From Nano- to Microsilver: Morphology Control and Shape Evolution of Facile One-Step Electrochemical Synthesis of Silver Particles on TiO<sub>2</sub> Nanotubes.

Abstract

Nano- and microsilver (Ag) exhibit a wide range of desirable catalytic, electronic, adsorption, and antimicrobial features, complementing the excellent properties of titanium dioxide (TiO₂) nanotubes by increasing their specific surface area. Formed via electrodeposition processes, it has advantages such as high purity; the methodology is repeatable, reproducible, fast, and easy. Anodically produced TiO₂ nanotubes were modified with nano- and microsilver by electrodeposition from silver nitrate solution using cyclic voltammetry and chronoamperometry. The mechanisms of electrodeposition and evolution of silver morphology were analyzed based on cyclic voltammograms/current density-time curves and micrographs taken using a scanning electron microscope. The variables were the AgNO₃ precursor solution's concentration, applied voltage, and number of cycles or deposition time. It was proven that there is a universal mechanism for the evolution of the morphology of the deposited silver, regardless of the electrodeposition method used. With the increase of the precursor concentration, deposition time, and applied voltage, the silver grows and reorients according to the following scheme: initially deposited Ag has the form of clusters of Ag nanoparticles resembling nanoflowers, nanoleaves, and spherical nanoparticles, which over time through aggregation create short dendrites and then develop subsequent multilevel branches to evolve into interconnected microsized particles.