## 3 Nanocomposite Catalysts
### Cold Atmospheric Pressure Plasmas Ex Situ Approach
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Support** & **Average Size of AuNPs** & \(\mathbf{k_{m}}\) & **Ref.** \\  & **(nm)** & **(mg\({}^{-1}\) min\({}^{-1}\))** & **Ref.** \\ \hline Aryl diazonium-modified olive waste & n.a. & 0.02 & [51] \\ PMMA & 7.0 & 0.37 & [52] \\ Magnetite microspheres & 5.0-7.0 & 1.22 & [53] \\ Reductive carbon dots & 15.0 & 0.10 & [54] \\ ZrO\({}_{2}\) & 17.0 \(\pm\) 5.1 & 0.06 & [56] \\ Egg-shell & 6.2 \(\pm\) 4.0 & 1.07 & [91] \\ Fe\({}_{3}\)O\({}_{4}\) & 15.0 & 13.8 & [92] \\ Sulfur doped graphitic carbon nitride & 12.0 & 1.50 & [93] \\ Quaternary ammonium hydrogel & 6.2 \(\pm\) 1.2 & 0.10 & [76]\({}^{*}\) \\ VBC/DVB with 1-amino-4-methylpiperazine ligands & 4.5 \(\pm\) 2.1 & 1.46 & [49]\({}^{*}\) \\ \hline \hline \end{tabular} \({}^{*}\) Works of the authors.  
\end{table} 
Table 4: Nanocomposite AuNPs-based catalysts for catalytic decomposition of 4-NP [49]. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Support** & **Nanoparticles** &
\begin{tabular}{c} **Increase of Heat** \\ **Transfer Rate** \\ \end{tabular} & **Ref.** \\ \hline polyaniline & CuO & 12–38\% & [88] \\ poly(N-isopropylacrylamide) & Graphene oxide & \(\sim\)200\% & [89] \\ stearic acid & Carbon nanotubes & 91\% & [90] \\ - & Cu, Al\({}_{2}\)O\({}_{3}\) nanofluid & 80\% & [27; 30] \\ Poly(vinyl pyrrolidone) & PtNPs & 800\% & [81]\({}^{*}\) \\ (vinylbenzyl)trimethylammonium & AuNPs & 300\% & [87]\({}^{*}\) \\ chloride-co-N,N–methylene bisacrylamide & & & \\ \hline \hline \end{tabular} \({}^{*}\) Works of the authors.  
\end{table} 
Table 3: Enhancement of heat transfer rates, using nanoparticle-based media. developed-for-that-purpose reaction-discharge system with pm-rf-APGD. Furthermore, by adjusting the frequency of the pm-rf-APGD, the duty cycle, the concentration of the Au(III) ions in the NPs precursor solution, and the flow rate of the AuNPs precursor solution, it was possible to predict the optimal working parameters under which the defined Au nanostructures would be produced. To reach this aim, the design of the experiment, along with the response surface methodology, was used to find the optimal working parameters of the proposed reaction-discharge system with pm-rf-APGD [84]. By adjusting the frequency to 1600 Hz, the duty cycle to 40%, the concentration of the Au(III) ions in the AuNPs precursor solution to 200 mg L\({}^{-1}\), and the flow rate of the nanostructures' precursor solution to 6 mL min\({}^{-1}\), it was possible to obtain the largest raw-AuNPs of average size of \(4.6\pm 1.0\) nm (as determined by TEM) [84]. Then, the size-controlled AuNPs were added to the solution consisting of the aqueous solution of gelatin and turmeric oil, forming the O/W nanoemulsion. The so-prepared nanofluid was used in the biomedical field, i.e., in the assessment of the migration and cytotoxic activity against the cancer cells' lines (human breast cancer cell lines MDA-MB-231 and MCF7 and non-tumor cell line MCF10A) [84]. Comparing our results to nanoemulsion with Au nanostructures produced by others (see Table 5), we found that the method proposed in our research group for nanostructures synthesis allows us to obtain NPs in one step and does not need an additional reducing agent to obtain the AuNPs. The mechanism of this O/W nanoemulsion with AuNPs' formulation was associated with capping the AuNPs with turmeric oil and gelatin, due to the presence of weak hydrogen bonds between AuNPs, turmeric oil, and gelatin [84]. In addition, the O/W nanoemulsion loaded with Au nanostructures revealed cytotoxicity toward human breast-cancer cell lines MDA-MB-231 and MCF7, which might define the further applications of so-obtained products. There are only few examples of similar approaches in the literature. [PERSON] et al. used the O/W nanoemulsion loaded with AuNPs in the inhibition of colon-cancer-cell growth [94]. Other examples, proposed by [PERSON] and [PERSON], did not provide the applications of the obtained nanoemulsion.