Tunable synthesis of nanoporous tin oxide structures on metallic tin by one-step electrochemical anodization

• Nanoporous tin oxide structures were synthesized by electrochemical anodization.
• The influences of anodizing conditions on structure features were investigated.
• i-t curves were used for the analysis of electrocrystallization process.
• Growth mechanisms in both kinetics and thermodynamics were proposed.

Nanoporous tin oxide structures were synthesized by electrochemical anodization of tin substrates at various anodizing conditions, including electrolyte species and concentration, anodizing potential, anodizing temperature and duration of the process. The influences of anodizing conditions on the structure features of anodized oxide films were investigated in detail. It is worth stressing that the correlation of the morphologies and current density virtue time curves (i-t curves) was analyzed in our work. The structure features of as-prepared tin oxide layers were found to be strongly related to anodizing conditions. Significant increases of average pore diameter occurred with the increase of anodizing potential, temperature and time. In addition, it is noteworthy that strong linear dependences between average steady-state current density and electrolyte concentration, anodizing potential as well as temperature were observed. It indicates the anodizing process is limited by mass transfer in electrolyte. Moreover, growth mechanisms in both kinetics and thermodynamics were established to elaborate the growth process of porous structures during anodization.