In recent years, Cu nanoparticle also has drawn a lot of attention due to its novel optical properties from surface plasmon resonance (SPR), which occurs when a light electromagnetic field drives the collective oscillation of free electrons in Cu nanoparticles (J. Many of these methods are conducted in liquid phase, which has the important advantage that nanoparticles can be formed in the presence of dispersing agents and no additional process for the addition of dispersing agents is required for the fabrication of inks to avoid the agglomeration. Huang et al., 1997 Qi et al., 1997 Ohde et al., 2001), thermal reduction ( Dhas et al., 1998), sonochemical reduction ( Dhas et al., 1998 Kumar et al., 2001), laser irradiation ( Yeh et al., 1999), and gamma radiolysis ( Joshi et al., 1998). Huang et al., 2006 Yu et al., 2007), chemical reduction ( Lisiecki & Pileni, 1993 Lisiecki et al., 1996 H. Cu nanoparticles have been synthesized by various reduction processes from cuprous (Cu(I)) or cupric (Cu(II)) compounds, including direct electrochemical reduction ( Han et al., 2006 L. Cu interconnects less than 20 μm wide can be made with a high resolution screen printer or a super inkjet printer using an ink which contains dense Cu nanoparticles. This chapter is written based on the result of the authors’ paper ( Yagi et al., 2009) with further detailed information on practical thermodynamic calculation and drawing procedure of potential-pH diagrams.Ĭopper (Cu) nanoparticles are of great interest in various fields, specifically that of printable electronics. The dependency of mixed potential on pH and temperature is discussed in the verification process. An extremely small activity of Cu 2+ aquo ion is achieved by using insoluble CuO powder as a Cu(II) ionic source, which is a key for the synthesis of nanosized particles. The advantage of this chemical reduction method is that abundant nanoparticles can be obtained for a short time by a simple operation. This concept is verified by selectively synthesizing Cu and Cu 2O nanoparticles from CuO aqueous suspension via chemical reduction using the concept as an example. By comparing kinetically determined mixed potential measured in reaction solution and thermodynamically drawn potential diagrams, e.g., potential–pH diagram, it is possible to know “what chemical species is stable in the reaction solution?.” It is predicted from potential-pH diagrams that nanoparticles in different oxidation states can be selectively synthesized by controlling the mixed potential. In this chapter, a general concept using potential-pH diagrams is described for oxidation-state control of nanoparticles synthesized via chemical reduction (also called electroless deposition or liquid-phase reduction). In the past, many synthesis methods of nanoparticles have been reported, but the synthesis processes have not been well discussed from the viewpoint of thermodynamics.
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