Preparation of nanoporous tin oxide by electrochemical anodization in alkaline electrolytes

This paper reports the creation of a porous tin oxide structure by means of anodization of pure tin foil in alkaline NaOH solutions. The tin oxide film formed is polycrystalline and possesses an irregular nanoporous structure with a porosity of ∼50%. The average pore size is ∼37 nm with a size distribution from 10 to 60 nm irrespective of anodization conditions, including the applied voltage (5–15 V) and NaOH concentration (0.125–1 M). The BET specific surface area of this porous structure is 79.6 m2/g. Linear relationships are observed for the dependence of tin oxide layer thickness on anodization time, applied voltage, and NaOH concentration. A thermodynamic model is established to explain the pore growth mechanism in the anodization process.

► Irregular nanoporous SnO2 films are created by anodization of tin in NaOH solution.
► Average pore diameter remains constant irrespective of applied voltage and NaOH concentration.
► Porous SnO2 film thickness increases linearly with time, voltage, and NaOH concentration.
► The formation of the porous structure is explained using a thermodynamic model.