Formation of Dendritic Metal Crystals in Aqueous Solutions Through Direct Electric Current
Electrolysis has long been a well-known and relatively widespread process in education at primary and secondary schools, which is used mainly as a demonstration experiment in front of students. We most often encounter simpler applications (for example, electrolysis of water or sodium or copper (II) chloride solution). This paper is focused on the lesser-known electrolysis of aqueous solutions of metal salts, which precipitate in a crystalline form in the form of micro trees (dendrites) when an electric current passes through it. For example, dendrites of tin, lead, silver, or copper, which differ in shape, can be prepared in this way. Dendrites are stable and can be easily isolated from a solution. The purpose of the paper is to bring electrolysis closer to high school students, which is effective and very interesting for them, but at the same time financially inexpensive and saves time, because these crystallizations take place in minutes and students can directly observe the nascent product. The paper also evaluates selected conditions (the influence of the substances used and their concentration in a solution, size of applied voltage, electrode material), which can have a fundamental influence on the rate of crystal formation or their shape and size. The theoretical background of electrolysis is mentioned only marginally in the paper, because it is quite extensive, complex, and not crucial for the given matter.
electrolysis, dendrites, metals, silver, copper, lead, tin, redox process
Břížďala, J. (2021). E-ChemBook: Multimediální učebnice chemie pro gymnázia. http://e-chembook.eu/elektrolyza, staženo 28. 12. 2021.
Carmody, W. R., & Wiersma, J. (1967). A study of the silver tree experiment. Journal of Chemical Education, 44(7), 417. https://doi.org/10.1021/ed044p417
Han, J. H., Khoo, E., Bai, P., & Bazant, M. Z. (2014). Over-limiting current and control of dendritic growth by surface conduction in nanopores. Scientific reports, 4(1), 1-8. https://doi.org/10.1038/srep07056
He, Y., Ren, X., Xu, Y., Engelhard, M. H., Li, X., Xiao, J., ... & Wang, C. (2019). Origin of lithium whisker formation and growth under stress. Nature nanotechnology, 14(11), 1042-1047. https://doi.org/10.1038/s41565-019-0558-z
Kim, S. J., Ko, S. H., Kang, K. H., & Han, J. (2010). Direct seawater desalination by ion concentration polarization. Nature nanotechnology, 5(4), 297-301. https://doi.org/10.1038/nnano.2010.34
Ma, M. C., Li, G., Chen, X., Archer, L. A., & Wan, J. (2021). Suppression of dendrite growth by cross-flow in microfluidics. Science advances, 7(8), eabf6941. https://doi.org/10.1126/sciadv.abf6941
Parvez, K., Li, R., Puniredd, S. R., Hernandez, Y., Hinkel, F., Wang, S., XinLiang, F., Mullen, K. (2013). Electrochemically exfoliated graphene as solution-processable, highly conductive electrodes for organic electronics. ACS nano, 7(4), 3598-3606. https://doi.org/10.1021/nn400576v
Tin dendrite. Mel Science. https://bit.ly/3nXWpEL, staženo 28. 12. 2021.
Vacík, J. (1995). Přehled středoškolské chemie. 3. dopl. vyd., SPN – pedagogické nakladatelství. ISBN 80-85937-08-5.
Xu, C., Zhang, Y., Fan, C., & Abys, J. A. (2005). Driving force for the formation of Sn whiskers: compressive stress-pathways for its generation and remedies for its elimination and minimization. IEEE Transactions on Electronics Packaging Manufacturing, 28(1), 31-35. https://doi.org/10.1109/TEPM.2005.846461
Yu, P., Lowe, S. E., Simon, G. P., & Zhong, Y. L. (2015). Electrochemical exfoliation of graphite and production of functional graphene. Current opinion in colloid & interface science, 20(5-6), 329-338. https://doi.org/10.1016/j.cocis.2015.10.007
Zýka J. a kol. (1979). Analytická příručka Díl I. 3. vyd. Praha: SNTL – Nakladatelství technické literatury. ISBN 04-612-79.