**4. Synthesis of nanomaterials with enhanced catalytic activity**

In order to improve the energy‐conversion efficiency in fuel cells, we loaded Pt nanoparticles on carbon nanoballs (CNBs) by SPP by reducing Pt ion on CNB surface via a surfactant molecule.In this study, we employed poly (vinylpyrrolidone)(PVP) or sodium dodecyl sulfate (SDS) to prepare Pt nanoparticles supported on CNB (Pt/CNB) by the SPP, and the electro‐ chemical properties as catalyst were evaluated by cyclic voltammetry (CV) [14].

**5. Conclusions**

powerful tool in nanotechnology.

Science, and Technology (MEXT)

, Maria Antoaneta Bratescu1

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1 EcoTopia Science Institute, Nagoya University, Nagoya, Japan

2 Green Mobility Collaborative Research Center, Nagoya University, Nagoya, Japan

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**Acknowledgements**

**Author details**

Osamu Takai1

**References**

2003‐2011.

SPP is a rapid, useful method for nanomaterials synthesis. The complexity of the phenomena makes this method a field of fundamental investigations. A better knowledge of the chemical reactions inside the plasma gas phase, liquid phase, and interfaces can make SPP a more

This work was partially supported by ʺTokai Region Nanotechnology Manufacturing Clusterʺ sponsored by Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Core Research for Evolutional Science and Technology (CREST) of Japan Science and Technology (JST) Agency, and Global COE Project, sponsored by Ministry of Education, Culture, Sports,

, Tomonaga Ueno2 and Nagahiro Saito1

Synthesis of Nanomaterials by Solution Plasma Processing 119

CNBs were prepared by thermal decomposition process of ethylene and hydrogen gases. During the synthesis process, the color of the solution changed from yellow to dark brown indicating the improvement of the dispersibility of CNB in solution. Moreover, TEM images and elemental mapping images showed the Pt NPs supported on CNB.

The catalytic activity of the Pt/CNB using SDS as surfactant was shown to be higher than the Pt/CNB prepared with PVP system. The SDS‐containing Pt/CNB also showed the higher activity than that obtained by the conventional chemical method.

We also studied the influence of the solution pH on the size of Pt NPs supported on CNBs and the catalytic activity of the composite nanomaterial. Figure 10 shows the influence of solution pH on the size and catalytic activity of synthesized Pt NPs supported on CNBs. From TEM images of Pt NPs on CNBs for solutions with various pH we can observe that the average size of Pt NPs is decreasing as the solution pH increases. The HRTEM image of Pt NP on carbon shows the crystalline structure of Pt NP and the organic surrounding surfactant PVP. The cyclic voltammetry measurements of Pt@CNBs show that small size Pt NPs have high catalytic activity (Figure 10(d)).

**Figure 10.** Influence of solution pH on the size and catalytic activity of synthesized Pt NPs supported on CNBs. (a) TEM images of Pt NPs on CNBs for solutions with various pH, indicating the average size of Pt NPs. (b) HRTEM image of Pt NP on carbon, with the organic surrounding PVP. (c) EDS mapping of Pt NPs. (d) Cyclic voltammetry measurements of Pt@CNBs.
