Nonlinear Self-Organizing Kinetics In The Electrochemical Growth Of Alumina Nanopore Arrays

Porous anodic alumina arrays (PAA) are widely applicated in nano model, catalysis,photovoltaic energy and biological sensors. Electro-oxidation is an importantpreparation method for nano-array oxide. Generally, porous anodic alumina arrays havebeen regarded to be resulted from the pitting corrosion of oxide by local excess H+onthe electrode surface with the assistance of anionic ligand. However, it is difficult toexplain the electrochemical oscillation (EO) and the homogeneity along the direction ofthe nanopore’s depth, reasonably. Exploring the formation mechanism of porousalumina film does great significance on improving these materials.In this paper, the nonlinear kinetics during the electrosynthesis of PAA wasinvestigated. The reaction kinetics of self-organization mechanism was determinedbased on the electrochemical impedance test and the analysis of the equivalent circuit.Nonlinear dynamic equations were established and analyzed in order to reveal therelationship between the spatial periodicity of the nano array and the time periodicity ofelectrolytic current. Then, the reliability of the reaction kinetics mode was verified bychanging the electrolytic voltage, electrolyte concentration testings. As the expansion ofnonlinear reaction kinetics mechanism, BZ oscillation in pure organic solvent alsoexplored in this study.The results of PAA research show that the nanoscale periodic PAA is formed by theself-organization in the alumina gel. The characteristic of the EO also changes alongwith the nanostructure. It was proved that the current oscillation is related with theselfcatalysis of condensation cations in the compact alumina gel close to the electrodesurface. The periodic nanostructure is formed by the self-organization of thecondensation cations in the outer layer of the reaction-diffusion coupled colloid system.This study first reveals the importance of the diffusion of micelle-like intermediates inthe formation of the nano-ordered structure. Thus, it may provide new ideas for batchsynthesis of ordered nanomaterials and materials with advanced structures.The results of BZ oscillation in pure organic solvent show that1-ethyl pyridinebromate ionic liquids can replace bromate of BZ reaction in water system. When pureacetonitrile as the solvent, perfect BZ reaction can be achieved in the mixed solutionconsist of malonic acid, ammonium cerium nitrate,1-ethyl pyridine bromate ionicliquids. Compared with the traditional BZ oscillation signal, this system shows the characteristics of large oscillation amplitude, long oscillation time. The most importantis that auxiliary acid can not be used in this system. In a word, we realized the BZoscillation from water system to the pure organic system. Which is breakthrough forsolving some scientific problems, such as organic metabolism of organisms in theenvironment without water, mineral flotation, new catalytic preparation ofnanomaterials.