SCIENTIFIC HIGHLIGHTS
The complex oxidation of copper and interconversion between phases formed yields in this work an oscillating redox gradient, thanks to the great resistance change when the oxidized phases are formed. Parallel stripes containing mainly Cu2O, CuO, and Cu(OH)2 with large resistance are formed perpendicular to the electric field, forming a sequence of secondary dipoles in intermediate Cu stripes, that depends on the external voltage applied, and that oscillates in time at the same spatial coordinates. With longer times, copper solubilizes at the larger induced potential zones, probably as Cu(OH)42−. A simple finite element electrostatic model defines the complex potential waves induced in the piece. The resulting dynamics offer an example of the complexity of order in unwired conducting materials in wet media, either in catalysis, bioelectrodes, electronics, photovoltaics, or energy storage.
Sustainable energy conversion & storage systems
Oscillatory patterns in redox gradient materials through wireless bipolar electrochemistry. The dynamic wave-like case of copper bipolar oxidation
L. Fuentes-Rodríguez, E. Pujades, J. Fraxedas, A. Crespi, K. Xu, L. Abad and N. Casañ-Pastor *

