Electroless Deposition of Base Metals at the Liquid/Liquid Interface of Ionic Liquids

Abstract

Metal nanostructures can be formed at the electrochemical liquid/liquid interface, so-called ITIES. Our group has presented a method to form metal nanostructures at the liquid/liquid interface between ionic liquid (IL) and water (W) [1-10]. This IL/W method utilizes the spatial selectivity of the reaction site only at the liquid/liquid interface, which is achieved by the separation of metal precursor ions dissolved in the W phase and reducing agent in the IL phase. The metal reduction reaction is regarded as the electron transfer across the IL/W interface, which enables us to analyze the reaction process with liquid-liquid electrochemistry at the IL/W interface [11]. Moreover, the usage of ILs (not molecular oils) leads to the formation of 1-dimensional (1D) nanostructures despite the inherent 2D geometry of the liquid/liquid interface, as a result of the structure-forming ability of ILs at the air [12-14], liquid [14-16], and solid [17-19] interfaces. By using this IL/W method, we have successfully prepared 1D nanostructures of noble metals such as Au [1,6], Ag [7], Pt [3], and Pd [5,6], and also their composites with polymer [2] and nanocarbons [8-10].In this presentation, we would like to introduce our very recent efforts to develop a sister method that uses another liquid/liquid interface between IL and oil (O). Wet chemical techniques for the metal nanostructure formation in general, including our IL/W method described above, involve water and therefore cannot escape from the limitation of metal elements to noble ones. In contrast, the IL/O method [20-22] is water-free and therefore can be used even for base metals, expanding the applicability and versatility of wet chemistry for metal nanostructure formation. In the presentation, we introduce our water-free liquid/liquid interface method, the electrochemical measurements of the electron and ion transfers across the interface, and the obtained nanostructures of base metals such as zinc, aluminum, and magnesium. References Nishi, T. Kakinami, T. Sakka, Chem. Commun., 51 (2015) 13638. Nishi, I. Yajima, K. Amano, T. Sakka, Langmuir, 34 (2018) 2441. Zhang, N. Nishi, K. Amano, T. Sakka, Electrochim. Acta, 282 (2018) 886. Takagi, N. Nishi, T. Sakka, Chem. Lett., 48 (2019) 589. Zhang, N. Nishi, T. Sakka, ACS Appl. Mater. Interfaces, 11 (2019) 23731. Zhang, N. Nishi, T. Sakka, Electrochim. Acta, 325 (2019) 134919. Zhang, N. Nishi, T. Sakka, Colloids Surf. A, 597 (2020) 124747. Zhang, N. Nishi, I. Koya, T. Sakka, Chem. Mater., 32 (2020) 6374. Koya, T. Sakka, N. Nishi, Langmuir, 37 (2021) 9553. Koya, Y. Yokoyama, T. Sakka, N. Nishi, Chem. Lett., 51 (2022) 643. Kakiuchi and N. Nishi, Electrochemistry, 74 (2006) 942. Nishi, Y. Yasui, T. Uruga, H. Tanida, T. Yamada, S. Nakayama, H. Matsuoka, T. Kakiuchi, J. Chem. Phys., 132 (2010) 164705. Nishi, T. Uruga, H. Tanida, T. Kakiuchi, Langmuir, 27 (2011) 7531. Nishi, T. Uruga, H. Tanida, J. Electroanal. Chem., 759 (2015) 129. Katakura, K. Amano, T. Sakka, W. Bu, B. Lin, M. Schlossman, N. Nishi, J. Phys. Chem. B, 124 (2020) 6412. Ishii, T. Sakka, N. Nishi, Phys. Chem. Chem. Phys., 23 (2021) 22367. Nishi, J. Uchiyashiki, Y. Ikeda, S. Katakura, T. Oda, M. Hino, N. Yamada, J. Phys. Chem. C, 123 (2019) 9223. Nishi, T. Yamazawa, T. Sakka, H. Hotta, K. Hanaoka, H. Takahashi, Langmuir, 36 (2020) 10397. Nishi, J. Uchiyashiki, T. Oda, M. Hino, N. Yamada, Bull. Chem. Soc. Jpn., 94 (2021) 2914. Kuroyama, N. Nishi, T. Sakka, J. Electroanal. Chem., 881 (2021) 114959. Nishi, Y. Kuroyama, N. Yoshida, Y. Yokoyama, T. Sakka, ChemElectroChem, 10 (2023) e202201000. Yoshida, Y. Yokoyama, T. Sakka, N. Nishi, to be submitted.