Electrochemical growth and characterization of micro/nanostructured SnOx with crater-like morphology

A comprehensive study concerning the mechanism of electrochemical growth of hierarchical SnOx nanostructures via electrochemical oxidation of metallic tin is presented. Materials were synthesized by simple one-step anodization carried out in a strongly alkaline electrolyte (1 M NaOH) under a potentiostatic regime (11 V) for various durations (2.5-30 min). Morphological features of the obtained materials were carefully investigated by FE-SEM. It was proven that upon prolonging anodization time, the initially formed compact oxide layer is gradually converted into the characteristic crater-like structures. Such hierarchically aligned materials are comprised of the compact middle part being the remnants of the passive film and highly porous slopes with a typical, highly-cracked morphology with channels having diameters of between 90 and 100 nm. The chemical composition of obtained materials was examined using X-ray powder diffraction (XRPD), and Raman spectroscopy confirming that after thermal treatment in air at 200 degrees C SnO, together with Sn3O4 forms are present within the highly-defective SnOx matrix. The photocatalytic performance of the annealed samples was also verified by monitoring the rate of decolorization of methylene blue (MB) under simulated sunlight. The achieved degradation efficiency of similar to 84% after 180 min of irradiation confirmed the broad potential of such kind of anodic tin oxide layers in photocatalytic applications.

Automated summary

A comprehensive study on the electrochemical growth mechanism of hierarchical SnOx nanostructures was conducted. It was found that the initially compact oxide layer gradually transformed into characteristic crater-like structures with prolonged anodization time. The obtained materials exhibited highly porous slopes with cracked morphology. XRPD and Raman spectroscopy confirmed the presence of SnO and Sn3O4 forms in the thermally treated samples. Moreover, the annealed samples showed promising photocatalytic performance, with a degradation efficiency of approximately 84% after 180 minutes of irradiation.