7. Conclusions

capacitance of f-SWCNT/Co3O4 is high with a value of 343F=g, while that of the Co3O4 nanoparticles is only 77F=g (Figure 17). Zarnegar et al. [27] used a new sonochemical synthesis of polyhydroquinolines having as catalyst Co3O4-CNT nanocomposites for aldehydes, dimedone, ethyl acetoacetate, and ammonium acetate in an ethanol medium. These nanocomposites proved to be a highly effective

TEM results of MWCNT-Co3O4 nanoparticles [27], (a) Co3O4, (b) MWCNT, (c) MWCNT-Co3O4

nanoparticles at 100 nm range and (d) MWCNT-Co3O4 nanoparticles at 100 nm range.

Figure 17.

Figure 18.

46

Synthesis procedure of MWCNT-Co3O4 nanoparticles [26].

Cobalt Compounds and Applications

The cobalt oxide-based composite nanoparticles and its engineering and medical applications were discussed in this book chapter. The pure Co3O4 nanoparticles reveal the presence of toxicity, whereas cobalt compounds are nontoxic. In this book chapter, the synthesis procedure for cobalt and cobalt-based compounds such as GO/Co3O4, ND-Co3O4, zeolite Y/Co3O4, and MWCNT-Co3O4. All the synthesized cobalt-based compound materials present magnetic properties, which can be benefit for the thermal applications, electrical applications, and medical applications. Cobalt oxide-based compounds have improved synergistic properties as compared to pure cobalt oxide nanoparticles.

### Acknowledgements

The author (LSS) acknowledges the Foundation for Science and Technology (FCT, Portugal) for the financial support received through the grant SFRH/BPD/ 100003/2014. The author (ACMS) acknowledges the 2017 Visiting Scientist Fellowship awarded to him under the Chinese Academy of Sciences President's International Fellowship Initiative. TEMA/DEM researchers also acknowledge the FCT grant UID/EMS/00481/2019-FCT, the infrastructures support CENTRO-01-0145- FEDER-022083-Centro Portugal Regional Operational Programme (Centro2020), and Project 33912-AAC no. 03/SI/2017, under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund.

## Author details

Lingala Syam Sundar<sup>1</sup> \*, Manoj K. Singh1,2\*, António M.B. Pereira1 and Antonio C.M. Sousa<sup>1</sup>

1 Department of Mechanical Engineering, Centre for Mechanical Technology and Automation (TEMA-UA), University of Aveiro, Portugal

2 Centre for Nano and Material Sciences, JAIN (Deemed-to-be University), Bengaluru, Karnataka, India

\*Address all correspondence to: sslingala@gmail.com and mksingh@ua.pt

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
