title: Nanoparticle Shape Evolution and Proximity Effects During Tip-Induced Electrochemical Processes.
abstract: Voltage spectroscopies in scanning probe microscopy (SPM) techniques are widely used to investigate the electrochemical processes in nanoscale volumes, which are important for current key applications, such as batteries, fuel cells, catalysts, and memristors. The spectroscopic measurements are commonly performed on a grid of multiple points to yield spatially resolved maps of reversible and irreversible electrochemical functionalities. Hence, the spacing between measurement points is an important parameter to be considered, especially for irreversible electrochemical processes. Here, we report nonlocal electrochemical dynamics in chains of Ag particles fabricated by the SPM tip on a silver ion solid electrolyte. When the grid spacing is small compared with the size of the formed Ag particles, anomalous chains of unequally sized particles with double periodicity evolve. This behavior is ascribed to a proximity effect during the tip-induced electrochemical process, specifically, size-dependent silver particle growth following the contact between the particles. In addition, fractal shape evolution of the formed Ag structures indicates that the growth-limiting process changes from Ag(+)/Ag redox reaction to Ag(+)-ion diffusion with the increase in the applied voltage and pulse duration. This study shows that characteristic shapes of the electrochemical products are good indicators for determining the underlying growth-limiting process, and emergence of complex phenomena during spectroscopic mapping of electrochemical functionalities.
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.|Center for Correlated Electron Systems, Institute for Basic Science (IBS) , Seoul 151-742, Republic of Korea.|Department of Physics and Astronomy, Seoul National University (SNU) , Seoul 151-742, Republic of Korea.
authors.forename: Sang Mo
authors.initials: SM
authors.lastname: Yang
authors.affiliation: Chemical Sciences Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: Mariappan Parans
authors.initials: MP
authors.lastname: Paranthaman
authors.affiliation: Center for Correlated Electron Systems, Institute for Basic Science (IBS) , Seoul 151-742, Republic of Korea.|Department of Physics and Astronomy, Seoul National University (SNU) , Seoul 151-742, Republic of Korea.
authors.forename: Tae Won
authors.initials: TW
authors.lastname: Noh
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: Sergei V
authors.initials: SV
authors.lastname: Kalinin
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: Evgheni
authors.initials: E
authors.lastname: Strelcov
keywords: diffusion-limited aggregation; electrochemistry; fractal; proximity effect; scanning probe microscopy; silver