Electrochemical Codeposition of TiO2 Nanoparticles with Zinc
Authors: Camargo Magali Karina , Schmidt Udo , Bund Andreas 
Published: February 2020

The preparation of metal matrix composite layers by codeposition of metal oxide nanoparticles during the zinc electrodeposition process is a convenient and low-cost methodology for the synthesis of functional coatings. Zn-TiO2 composite layers can be used in the field of protective coatings for steel as they can offer enhanced properties such as hardness, wear and corrosion resistance. On the other hand, due to the photocalytic properties of TiO2, the layers are promising candidates for water remediation technologies as they can be used as cheap electrodes for polluted water treatment. The photocatalytic activity of the composite layer can be further increased by heat treatment of the layer in order to get ZnO, which also has photocatalytic properties [1].
Generally, the successful achievement of the properties described above is directly related to the amount of particle incorporation, their uniform distribution within the metal matrix as well as the resulting microstructure of the metal matrix. Usually the amount of codeposited metal oxide particles in zinc electrodeposits is relatively low (less than 0.7 wt.%) [2-4], which demonstrates that the electro-codeposition of metal oxides with zinc is still challenging.
This contribution will discuss different approaches pursued in the authors' labs towards the successful incorporation of TiO2 nanoparticles during zinc electrodeposition. The pathways used in this work involve the study of the influence of:
i) The electrolyte chemistry and the dispersion stability of nanoparticles in the plating bath: role of the anion type (e.g. Cl-, SO4
2-) present in the electrolyte [5] as well as the use of plating additives.
ii) The electrodeposition method: galvanostatic deposition, pulse plating and ultrasound assisted deposition [6].
iii) The surface chemistry of the particles: surface modification of TiO2 with specific molecules acting as “coupling agents” between TiO2and zinc.
The results will be discussed with special focus on the characterization of particle incorporation (GD-OES), the microstructural (XRD) and morphological (SEM, FIB) properties as well as the mechanical properties. By using suitable parameters, the successful co-deposition of TiO2 nanoparticles could be achieved. The resulting layers exhibit diverse structures and properties leading to a variety of potential applications. In addition, the pros and cons of the employed methodologies will be discussed.

References

1. T. Frade, M. E. Melo Jorge and A. Gomes, Surface & Coatings Technology, 206, 3459-3466 (2012).
2. T. Frade, V. Bouzon, A. Gomes, and M. I. da Silva Pereira, Surf. Coat. Technol., 204, 3592–3598 (2010).
3. T. R. Khan, A. Erbe, M. Auinger, F. Marlow, and M. Rohwerder, Sci. Technol. Adv. Mater., 12, 055005 (2011).
4. D. Aslanidis, J. Fransaer, and J. P. Celis, J. Electrochem. Soc., 144, 2352–2357 (1997).
5. M. K. Camargo, U. Schmidt, R. Grieseler, M. Wilke, and A. Bund, J. Electrochem.
Soc., 161, D168–D175 (2014).
6. M. K. Camargo, I. Tudela, U. Schmidt, A.J. Cobley and A. Bund, Electrochimica Acta, 198, 287-295 (2016).

Figure 1