Unique Layered Tin Oxide Structure Via Buffered Anodization

Abstract

The electrochemical anodization of various metals (e.g., Al [1], Ti [2] and Fe [3]) is able to generate a great variety of nanostructures. In the last decade, these new nanomaterials have received intensive interest due to their high technological potential in many applications such as photocatalysts for organic degradation [4], self-cleaning substrates [5] and solar cell electrodes [6, 7].Tin dioxide (SnO2) is an n-type semiconductor used as solid-state gas sensor [8] and oxidation catalyst [9]. It also has the potential to function as high capacity anode material for lithium-ion batteries [10]. Jeun et al. [11] synthesized irregular nanoporous tin oxide films in 0.3 M oxalic acid solution at 6 V and used it as a gas sensor material.Anodization of tin in oxalic acid solutions at an applied voltage of above 5 V produces highly porous tin oxide structures. Lower applied voltages, as investigated by Yang et. Al [12], result in a passivation of the surface by precipitation of tin-oxalate.We investigated the use of a buffer solution to prevent the precipitation of tin oxalate unto the surface. This enabled us to anodize tin at lower applied voltages resulting in a completely new tin / tin dioxide layer structure.After optimizing the parameters, we investigated the growth mechanism and various chemical, physical and biological applications of this new structure.Literature:[1] H. Masuda, K. Fukuda, Science 268 (1995) 1466[2] D. Gong, C.A. Grimes, O.K. Varghese, W. Hu, R.S. Singh, Z. Chen, E.C. Dickey, J. Mater. Res. 16 (2001) 3331[3] T.J. LaTempa, X. Feng, M. Paulose, C.A. Grimes, J. Phys. Chem. C 113 (2009) 16293[4] K. Lee, D. Kim, P. Roy, I. Paramasivam, B. Birajdar, E. Spiecker, P. Schmuki, J. Am. Chem. Soc. 132 (2010) 1478[5] E. Balaur, J.M. Macak, H. Tsuchiya, P- Schmuki, J. Mater. Chem. 15 (2005) 4488[6] O.K. Varghese, M. Paulose, C.A. Grimes, Nat. Nanotechnol. 4 (2009) 592[7] G.K. Mor, K. Shankar, M. Paulose, O.K. Varghese, C.A. Grimes, Nano Lett. 6 (2006) 215[8] P.G. Harrison, C. Bailey, W. Azelee, J. Catal. 186 (1999) 147[9] G. Croft, M.J. Fuller, Nature 269 (1977) 585[10] Y. Wang, J.Y. Lee, H.C. Zeng, Chem. Mater. 17 (2005) 3899[11] J.-H. Jeun, H.-S. Ryu, S.-H. Hong, J. Electrochem. Soc. 156 (2009) 263[12] M. Wang, Y. Liu, D. Zhang, H. Yang, Electrochim. Acta 59 (2012) 441