Photoelectrocatalysis is a technique with consolidated principles that has gained prominence and has been successfully applied in organic compound oxidation, microorganism inactivation, CO₂ reduction energy[1]. Their application on wastewater treatment is based on the use of a semiconductor that generates charge carriers (e-/h+) when irradiated by light energy equal or greater than its band gap and simultaneously biased by a gradient potential. The recent progress of photoelectrocatalysis is intimately related to the advances in materials science, especially in nanomaterials. Other challenges are the development of stable semiconductor materials able to be activated by solar irradiation.

Among the numerous types of semiconductors used as photocatalysts, tin oxides with different forms (SnO, SnO₂ and Sn₃O₄), present wide-spread applications, because of its abundant availability and non-toxicity. The aim of this work was to perform the synthesis of a Sn₃O₄ ordered structure under mild operational conditions to further apply it in the photoelectrocatalytic degradation of a dye, taken Acid Yellow 17 as a model of textile dye treatment. The hierarchical form of Sn₃O₄, with the flower-like nanostructure with triclinic Sn₃O₄/Ti, was successfully prepared using microwave-assisted hydrothermal method at pH 6, in 150 ^oC. The as-prepared Sn₃O₄ was deposited in the titanium substrate using spin coating methods. The Sn₃O₄ /Ti nanostructure demonstrated high photocatalytic activity in the visible wavelength (λ>390 nm), calculated band gap of energy 2.4 eV by diffuse reflectance. The electrode was successfully applied on degradation of 10 ppm solution of AY17 (pH 4) at low bias potential (0.5 V) and visible light irradiation reached complete discoloration after only 30 min of treatment. The TOC removal reached 83% after 4000 s^-1 of light irradiation time. Therefore, the flower-like nanostructured Sn₃O₄ proved to be efficient in the visible light driven photoelectrocatalytic degradation of AY17 dye, which represents an energy-saving option for its future treatment and removal of the environment.

Acknowledgments

We acknowledge the financial support from INCT-DATREM, process FAPESP 14/50945-4 and CNPq 465571/2014-0.

References

[1] G. G. Bessegato, T. T. Guaraldo, J. F. de Brito,M. F. Brugnera, M. V. B. Zanoni, Electrocatal. 2015 6, 415–441.