title: Spatially Resolved Probing of Electrochemical Reactions via Energy Discovery Platforms.
abstract: The electrochemical reactivity of solid surfaces underpins functionality of a broad spectrum of materials and devices ranging from energy storage and conversion, to sensors and catalytic devices. The surface electrochemistry is, however, a complex process, controlled by the interplay of charge generation, field-controlled and diffusion-controlled transport. Here we explore the fundamental mechanisms of electrochemical reactivity on nanocrystalline ceria, using the synergy of nanofabricated devices and time-resolved Kelvin probe force microscopy (tr-KPFM), an approach we refer to as energy discovery platform. Through tr-KPFM, the surface potential mapping in both the space and time domains and current variation over time are obtained, enabling analysis of local ionic and electronic transport and their dynamic behavior on the 10 ms to 10 s scale. Based on their different responses in the time domain, conduction mechanisms can be separated and identified in a variety of environmental conditions, such as humidity and temperature. The theoretical modeling of ion transport through finite element method allows for creation of a minimal model consistent with observed phenomena, and establishing of the dynamic characteristics of the process, including mobility and diffusivity of charged species. The future potential of the energy discovery platforms is also discussed.
authors.affiliation: †School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
authors.forename: Jilai
authors.initials: J
authors.lastname: Ding
authors.affiliation: ‡Institute for Functional Imaging of Materials and Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
authors.forename: Evgheni
authors.initials: E
authors.lastname: Strelcov
authors.affiliation: ‡Institute for Functional Imaging of Materials and 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: †School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.|§G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
authors.forename: Nazanin
authors.initials: N
authors.lastname: Bassiri-Gharb
keywords: charge transport; ionic dynamics; nanostructured ceria; tr-KPFM