Nucleation and growth kinetics of electrochemically deposited ceria nanostructures for high-temperature electrocatalysis

Abstract

Cathodic electrochemical deposition, a simple and cost-effective route for fabricating ceria nanostructures, has attracted much attention in catalysis and renewable energy technologies. However, electrochemical nucleation and growth mechanisms that determine the nanoscale architecture of ceria films during deposition have not yet been clarified. In this study, we analyze current and mass-time transients and thin film microstructures as functions of applied potential and temperature. We then examine these results in light of analytical models for the determination of relative nucleation rate, nuclei density, and diffusivity of Ce ion during ceria electrocrystallization. As applied potential and temperature decrease, the reduced deposition rate allows nuclei to branch, leading to more 'petal'-like nanostructures with high specific surface areas. These optimized ceria nanostructures greatly improve the hydrogen electro-oxidation rate and reduced electrode resistance when coated onto a model electrode that simulates a Ni/yttria-stabilized zirconia composite anode utilized in solid oxide fuel cells. (C) 2019 Published by Elsevier Ltd.